Tucson monthly climate reports for 2023

The new year began on a wet note when a winter storm impacted the area as the calendar turned from 2022 to 2023. Although not as wet as what occurred when the calendar changed from 2021 to 2022, it did mark the first time in over 70 years that precipitation was recorded on back-to-back New Year's Day (1949-1951). Above normal temperatures then prevailed across the area until mid-month when an upper air pattern change occurred which would bring a series of winter storms to the area along with cooler than normal temperatures for the remainder of the month.

The first winter storm impacting the area during the second half of the month brought valley rain and mountain snow over a three day period from the 15th to the 17th. The passing of this system would usher in a much colder air mass that would remain across the area through the remainder of the month. Daily low temperatures across the metro from the 19th to the 22nd would range from the mid 20's to the lower 30's. A second winter storm, this one colder than the mid-month storm, would bring light snow/flurries down to the valley floor on the 23rd and early on the 24th. Afternoon temperatures on the 24th struggled to get out of the 40's. This system reinforced the cold air in place with lows on the 24th to 26th in the mid 20's to the lower 30's. The last five days of the month saw highs in the 60's and lows in the 30's.

The monthly average temperature of 51.6° is TWO degrees below normal and ranks as the 60th warmest January on record. Temperature extremes for the month ranged from a high of 80° on the 13th to a low of 27° on the 26th. The high on the 13th of 80° set a new daily record eclipsing the old record of 78° which originally occurred in 1928 and was later tied in 2000, 2006 & 2018. Below is a listing of some interesting temperature items that occurred during January.

• 14 straight days with below normal lows (18th to 31st); most in January since 16 straight days in 2011 to start the year.
• 14 straight days with lows colder than 40° (18th to 31st); most since 18 straight days which occurred from December 30, 2010 to January 16, 2011
• 11 straight days with lows 35° or colder (19th to 29th); most since 11 straight days which occurred from December 22, 2007 to January 1, 2008
• 4 straight days with lows 32° or colder (24th to 27th); most since 5 straight days which occurred in January 2017 (25th to 29th)
• # of January days with lows 28° or colder (3); most in January since 5 days in 2013
• # of January days with lows 32° or colder (6); most in January since 12 days in 2013
• # of January days with lows 33° or colder (9); most in January since 13 days in 2013
• # of January days with lows 35° or colder (11); most in January since 15 days in 2013

Rainfall amounts across the metro area, using several sources like rainlog.org, the Pima County Regional Flood Control District gages and CoCoRaHS, ranged widely from 0.75" to 3" with localized higher amounts across the Catalina Foothills. The International airport, which is the official recording spot in Tucson, recorded 1.76" which is just under one inch above normal and ranks as the 16th wettest January on record, tied with 1907. Some interesting rainfall items which occurred during January. These items are for the airport only.

• 3 straight days with daily rainfall totals of 0.40" or greater (15th to 17th); this is a record for January and the most in the calendar since 3 days in July 2021 (23rd to 25th)
• 2 straight days with daily rainfall totals of 0.50" or greater (16th & 17th); this is tied for a January record and the most in the calendar since 3 days in July 2021 (23rd to 25th).
• New daily rainfall record set on the 16th with 0.59". This broke the old record of 0.37" from 1987 and its the first daily rainfall record at the airport since July 25, 2021

One month remains in climatological Winter and so far it has been cooler (52.8° or -0.6°) and wetter (3.03" or +1.23") than normal. The 3.03" at the airport would rank as the 35th wettest Winter on record if no precipitation is recorded in February..

The Climate Prediction Center forecasts for temperature a 35% chance that they will end up below normal & a 32% chance that they will end up above normal. The forecast for precipitation is a 43% chance that they will end up below normal & a 24% chance that they will end up above normal.

The February outlook for Tucson, issued on January 31st by the Climate Prediction Center, slightly favored above-normal monthly mean temperatures (35% above vs 32% below) and favored below-normal total precipitation amounts (43% below vs 24% above).

The month was dominated by an active weather pattern that resulted in a roller-coaster ride in temperatures and an unusual number of windy days for February. This was thanks to a handful of winter storms that moved across the area that brought precipitation in the form of valley rain and mountain snow and on occasion, snow down to the valley floor (14th, 15th & 26th). The most significant winter storms occurred on the 14th-15th, 17th, 21st-22nd & 26th.

The monthly average temperature of 53.3° is 2.9° below normal and ranks as the 54th coolest February on record. This is the fourth February in the last five years that the average monthly temperature was below normal. Temperature extremes for the month ranged from a high of 80° on the 5th to a low of 28° on the 16th.

La Niña conditions that were present during the previous two winter seasons (December through February) continued into a third straight winter. This would be the third occurrence since 1950 that La Niña conditions would be present in the equatorial Pacific for three consecutive winters (1973-74 to 1975-76 & 1998-99 to 2000-01). Based on past La Niña impacts during the winter season, the temperature and precipitation outlook for Tucson, issued November 17th by the Climate Prediction Center, called for the following:

• a 23% chance that the seasonal mean temperatures will be below normal
• a 44% chance that the seasonal mean temperatures will be above normal
• a 43% chance that the seasonal total precipitation will be below normal
• a 24% chance that the seasonal total precipitation will be above normal

The seasonal average temperature of 53.0° is 1.3° below normal and goes into the record books as the 54th warmest on record, tied with Winter 1910-11 & Winter 1968-69. Temperature extremes ranged from a high of 80° on January 13th & February 5th to a low of 27° on January 26th. Ten days recorded freezing low temperatures at the airport, which is normal. However, this is two more days than what occurred during the previous two winter seasons combined. Additionally, there were two record temperatures that were established. They were:

• A record warm low temperature on December 4 (59°; old record 56° in 1946)
• A record high temperature on January 13 (80°; old record 78° in 1928, 2000, 2006 & 2018)

Precipitation across the metro area, using several sources like rainlog.org, the Pima County Regional Flood Control District gages, and CoCoRaHS, ranged widely from 2.50" to 6.50" with the highest totals occurring in Oro Valley and along the Catalina foothills. The Tucson International airport, which is the official recording location in Tucson, recorded 3.62" which is just under one inch above normal and ranks as the 26th wettest Winter season on record.

Dating back to 1950, there have been twenty-five occurrences that La Niña conditions were present during climatological winter. Winter 2022-23 became only the 2nd La Niña winter to record above-normal seasonal precipitation. The other occurrence was Winter 1984-85 when 6.09" was recorded. Note: Winter seasonal total precipitation for the twenty-five La Niñas were compared to the 30-year climatological normal total for Tucson at the time of occurrence.

The yearly mean temperature of 52.4° is around 2.5° below normal and ranks as the 59th coolest January/February period on record.

Precipitation across the metro area has ranged widely from 1.50" to 4.50" during the first two months of the year. The Tucson International airport, the official recording location in Tucson, has recorded 2.35" which is three-quarters of an inch above normal and ranks as the 32nd wettest January/February period on record.

The March outlook from the Climate Prediction Center for Tucson slightly favors below-normal monthly mean temperatures (34% below vs 33% above) and above-normal total precipitation amounts (37% above vs 30% below).

The Spring season outlook from the Climate Prediction Center for Tucson favors above-normal seasonal mean temperatures (46% above vs 21% below) and below-normal total precipitation amounts (41% below vs 26% above).

The month started with a winter storm moving through the area, bringing widespread snow to the metro area late on the 1st through the morning hours of the 2nd. Snowfall totals across the metro area ranged from 1" to 4" with isolated totals up to 7" on the far southeast side in and around Vail.

In the wake of the winter storm, there was an extended period of dry weather along with above-normal temperatures from the 4th through the 14th. High temperatures were in the 70s to lower 80s with lows mostly in the 40s and 50s.

An active weather pattern settled in for the next 10 days which brought showers to the area on the 15th, 16th, and 22nd. High temperatures were below normal with daily highs in the 60s to mid-70s.

The warmest high temperatures of the month occurred on the 28th and 29th with readings in the lower 80s.

The monthly average temperature of 59.1° is just under THREE degrees below normal and ranks as the 63rd warmest March on record. Temperature extremes for the month ranged from a high of 83° on the 28th & 29th to a low of 33° on the 1st and 2nd.

Rainfall amounts across the metro area, using several sources like rainlog.org, the Pima County Regional Flood Control District gages, and CoCoRaHS, were mostly below 0.75" with isolated spots up to 1". The International airport, which is the official recording spot in Tucson, recorded 0.66" which ranks as the 42nd wettest March on record. The 0.66" is a tenth of an inch above normal ends a streak of "18" straight Marches that were below normal. The last March to record above-normal rainfall before this year was in 2004 when 1.12" was recorded. The 30-year normal at the time (1971-2000) was 0.81".

To say that the first three months of 2023 have been pleasantly cool is an understatement. Due to an unusually active weather pattern during the most recently ended La Niña event, the coolest first quarter of the year since 2001 had an average yearly temperature of 54.7°. This is just under THREE degrees BELOW normal and ranks as the 64th warmest or 64th coolest on record through the end of March. The average monthly temperature for the first three months has all been below normal. The last time that happened in Tucson was back in 1975 when the first six months of that year were below normal.

Rainfall at the Tucson International airport, the official location in Tucson, of 3.01" is a little over three-quarters of an inch ABOVE normal & ranks as the 31st wettest January through March period on record. The water year rainfall is at the halfway mark with a 4.81" being recorded at the airport. This ranks as the 50th wettest first half of the water year period.

The April outlook from the Climate Prediction Center for Tucson slightly favors below-normal monthly mean temperatures (34% below vs 33% above) and favors below-normal total precipitation amounts (45% below vs 22% above).

Coming off the coolest first quarter of the calendar since 2001, Tucsonans were hoping for that trend to continue in April. Although the month did start off cooler than normal through about the 10th, the remainder of the month was warmer than normal resulting in the first monthly mean temperature being above normal in 2023.

With the storm track retreating north as it does during the transition season, no rain was recorded in Tucson. The airport hasn't recorded measurable rain in April since April 11, 2020, or a span of 109 April days.

Plenty of interesting temperature outcomes occurred during April 2023. They are listed below.

• The low temperature on the 5th of 32° was the latest last freezing temperature of the cool season since 1936.
• The 32° low on the 5th was the 9th latest freeze date on record since 1895.
• In a two-day span, 97° on the 10th and 99° on the 11th, Tucson recorded the first high of every temperature in the 90s this year. Rather uncommon. What's interesting was how late or early the first occurrences were. For example, 1st 90° was 11 days late; 1st 95° was 14 days early & 1st 99° was 32 days early.
• The first 96°, 97°, 98° & 99° rank as 6th, 4th, 3rd, & 3rd earliest on record respectively.
• The first triple-digit high of 2023 occurred on the 30th at 1:59 PM. This ranks as the 7th earliest occurrence on record.
• First April on record which recorded a freezing low temperature & a triple-digit high temperature.
• April 2023 joins October 1929 & October 2020 as the only calendar months to record a freezing low temperature & a triple-digit high temperature.
• This is the 8th time that the first 100°+ high of the year has occurred in April.
• Eight of the earliest fourteen occurrences have occurred in the 21st century.

The monthly average temperature of 70.0° is just under two degrees above normal and ranks as the 14th warmest April on record. Temperature extremes for the month ranged from a high of 100° on the 30th to a low of 32° on the 5th. Three temperature records (two highs & one warm low) were set.

No rain was recorded across the metro area using sources like rainlog.org, the Pima County Regional Flood Control District gages, and CoCoRaHS. The zero rainfall recorded at the International Airport, which is the official recording spot in Tucson, marked the 31st time since 1895 that no measurable rain was recorded at the official site. This is the fourteenth April on record with ZERO rainfall and the sixteenth April in the past eighteen that the airport recorded below-normal rainfall.

The average yearly temperature of 58.5° is slightly over one and a half degrees below normal and ranks as the 42nd warmest on record, tied with 1916, 1976, 1978 & 1999, through the end of April. This is the first time since 1998 that the yearly average temperature for the first third of the calendar year is below normal. On both occasions, the departure from normal was 1.6°. The difference is that the current normal period (1991-2020) temperature through the end of April is 60.1° while back in 1998 the normal period (1961-1990) temperature through the end of April was 57.5°.

Rainfall at the Tucson International Airport, the official location in Tucson, of 3.01" is 0.53" above normal & ranks as the 46th wettest January through April period on record. The water year rainfall total of 4.81" ranks as the 57th wettest on record, tied with the 1936-37 water year.

The May outlook from the Climate Prediction Center for Tucson favors below-normal monthly mean temperatures (45% below vs 22% above) and equal chances (EC) of below, near, or above normal total precipitation amounts.

An unusual weather pattern mid-month, mentioned above, brought welcome rain to a normally dry month. This led to most of the area recording above-normal rainfall for the month. Using several sources like rainlog.org, the Pima County Regional Flood Control District gages and CoCoRaHS totals across the metro area ranged from a tenth of an inch (0.10") to one inch. The International Airport, which is the official recording spot in Tucson, recorded just over half an inch (0.53") which ranks as the 16th wettest May on record, dating back to 1895.

Spring 2023 was slightly cooler and slightly wetter than the 1991-2020 normal. If you recall the Spring season outlook for Tucson, issued on February 16th by the Climate Prediction Center, favored above-normal seasonal mean temperatures (46% above Vs 21% below) and below-normal total precipitation amounts (41% below Vs 26% above).

The seasonal average temperature of 68.7° was slightly below the 1991-2020 normal of 68.9° and goes into the record books as the 27th warmest on record, tied with 1954. The seasonal average temperature was below normal for the first time since 2019 and the 6th time since 1982. The other Springs in the past 40+ years that were below normal, when compared to their respective normal period, were 1983, 1991, 1998, 2010 & 2019.

Temperature extremes ranged from a high of 100° on April 30th to a low of 32° on April 5th. This is the first time on record that both the seasonal warmest high and coldest low temperatures occurred in April. This is the fifth time on record that the seasonal warmest Spring temperature occurred in April. This is also the ninth time on record that the seasonal coldest Spring temperature occurred in April.

There was only one triple-digit high temperature and that occurred on April 30th. Of the eight Aprils that have recorded a 100°+ high since 1895, this year joins 1992 as the only two in which May didn't record a 100°+ high.

Rainfall amounts across the metro area, using several sources like rainlog.org, the Pima County Regional Flood Control District gages, and CoCoRaHS, ranged from half of an inch (0.50") to one and a half inches (1.50") with localized spots up to two inches (2.00"). The International airport, which is the official recording spot in Tucson, recorded 1.19". This ranks as the 53rd wettest Spring on record.

2023

The average yearly temperature, through the end of May, of 62.4° is 1.1° below normal and ranks as the 31st warmest on record, tied with 1957, 1990 & 1995. The average yearly temperature was below normal at the end of May for the first time since 2019 and the 6th time since 1982.

Rainfall at the Tucson International Airport, the official location in Tucson, of just over three and a half inches (3.54") is just under nine-tenths of an inch above normal and ranks as the 36th wettest January through May period on record. The water year is above normal since October 1st at 5.34" which ranks as the 52nd wettest water year to date with four months left in the water year calendar.

The high temperature of 89° on the 1st was the first sub-90° high to start the month since 1991 when it was 80°. Another noteworthy temperature occurrence was the second triple-digit high of 2023 which occurred on the 4th. This was 35 days after the first triple-digit high of 2023 that occurred on April 30th. The 35 days set a record for the longest time between Tucson's 1st and 2nd occurrence. The previous record was 30 days in 1965.

The monthly average temperature of 84.5° is 1.6° below normal and ranks as the 44th warmest June on record, tied with 1992 & 2000. Temperature extremes for the month ranged from a high of 111° on the 25th & 26th to a low of 60° on the 1st. This is the first June since 2007 to have the warmest monthly low temperature not be 80° or warmer°.

Most of the metro area, using several sources like rainlog.org, the Pima County Regional Flood Control District gages and CoCoRaHS, recorded no rain. There were isolated spots on the morning of the 20th that recorded less than a tenth of an inch. The International airport, which is the official recording spot in Tucson, recorded zero rainfall. This is the 16th June in which the official recording location recorded zero rainfall.

The average yearly temperature, through the end of June, of 66.0° is 1.2° below normal & ranks as the 36th warmest on record. The negative departure from normal is the largest since 1998 when the departure from its respective normal was 1.7° below normal. The table below compares the average yearly temperature at the end of June for 1998 & 2023 with their respective 30-year normal period.

The July outlook from the Climate Prediction Center for Tucson favors above-normal monthly mean temperatures (39% above vs 28% below) and below-normal total precipitation amounts (45% below vs 22% above).

The monthly average temperature of 94.2° is a whopping 6.0° ABOVE normal and ranks as the following:

1. the HOTTEST July on record, shattering the previous July record of 91.5° from 2020, and
2. the HOTTEST single month on record, shattering the old record of 92.0° from August 2020.

Temperature extremes for the month ranged from a high of 112° on the 18th, 19th, 20th & 25th to a low of 71° on the 1st.

Below is an extensive listing of July temperature records that were set or tied:

• Hottest with an average temperature of 94.2° (old record 91.5° from 2020)
• Hottest average monthly high temperature of 108.4° (old record 105.1° from 1994)
• Warmest average monthly low temperature 80.0° (old record 79.0° from 2020)
• Set daily high temperature on 6th: 110° (old record 109° from 1989, 2005 & 2017)
• Tied daily high temperature on 15th: 110° (previously set in 1997 & 1998)
• Set daily high temperature on 16th: 111° (old record 110° from 2003 & 2009)
• Tied daily high temperature on 17th: 111° (previously set in 2005)
• Set daily high temperature on 18th: 112° (old record 109° from 1989 & 1992)
• Set daily high temperature on 19th: 112° (old record 109° from 2009)
• Set daily high temperature on 20th: 112° (old record 109° from 1989)
• Tied daily high temperature on 21st: 110° (previously set in 2006)
• Set daily high temperature on 22nd: 111° (old record 108° from 2006)
• Set daily high temperature on 25th: 112° (old record 110° from 2018)
• Tied daily high minimum temperature on 14th: 85° (previously set in 1925, 1936 & 2010)
• Tied daily high minimum temperature on 15th: 86° (previously set in 1979)
• Set daily high minimum temperature on 21st: 83° (old record 82° from 1932, 2004 & 2005)
• Tied daily high minimum temperature on 28th: 83° (previously set in 2000 & 2019)
• Set monthly occurrences of high temperatures 100° or hotter: 31 days (old record 28 days from 1920 & 1942)
• Set monthly occurrences of high temperatures 105° or hotter: 29 days (old record 23 days from 1994)
• Set monthly occurrences of high temperatures 110° or hotter: 14 days (old record 5 days from 1989)
• Tied monthly occurrences of low temperatures 80° or warmer: 16 days (previously set in 2020)
• Set monthly occurrences of low temperatures 85° or warmer: 5 days (old record 4 days from 2010)
• Set consecutive days with high temperatures 100° or hotter: 31 days (old record 22 days in 2005, 1st to 22nd)
• Set consecutive days with high temperatures 105° or hotter: 18 days from 13th to 30th (old record 16 days in 1994, 1st to 16th)
• Set consecutive days with high temperatures 110° or hotter: 8 days from 15th to 22nd (old record 4 days from 1995, 26th to 29th)
• Set consecutive days with low temperatures 80° or warmer: 10 days from 7th to 16th (old record 9 days from 2020, 7th to 15th)
• Set consecutive days with low temperatures 85° or warmer: 4 days from 12th to 15th (old record 2 days from July 1915, July 2006, July 2007 & July 2018)
• The monthly low temperature of 71° occurred on the 1st. Only three other Julys (2013, 2014 & 2015) had a monthly low temperature as warm as 71°. Yeah, an odd record to be recognized.

Although not a monthly record, the four days with highs of 112° (18th, 19th, 20th & 25th) rank, tied, as the 5th hottest July days on record.

Although not a monthly record, the low temperature of 87° on the 13th ranks tied as the 5th warmest July low temperature on record.

Below is an extensive listing of monthly temperature records that were set or tied in July:

• Hottest month: July 2023 with average temperature of 94.2° (old record 92.0° from August 2020)
• Hottest average monthly high temperature of 108.4° (old record 105.7° from June 1990)
• Warmest average monthly low temperature 80.0° (old record 78.7° from August 2020)
• Set monthly occurrences of high temperatures 100° or hotter: 31 days (old record 30 days from August 1994 and June 2013)
• Set monthly occurrences of high temperatures 105° or hotter: 29 days (old record 24 days from August 2020)
• Set monthly occurrences of high temperatures 110° or hotter: 14 days (old record 9 days from June 1990)
• Tied monthly occurrences of low temperatures 80° or warmer: 16 days (previously set in July 2020 & August 2020)
• Set monthly occurrences of low temperatures 85° or warmer: 5 days (old record 4 days from July 2010)
• Set consecutive days with high temperatures 100° or hotter: 31 days (old record 29 days August 1994, 1st to 29th)
• Set consecutive days with high temperatures 105° or hotter: 18 days from July 13th to 30th (old record 16 days from July 1994, 1st to 16th)
• Tied consecutive days with high temperatures 110° or hotter: 8 days from July 15th to 22nd (previously set in June 2021, 12th to 19th)
• Set consecutive days with low temperatures 80° or warmer: 10 days from July 7th to 16th (old record 9 days from June 2017 & July 2020)
• Set consecutive days with low temperatures 85° or warmer: 4 days from July 12th to 15th (old record 2 days from July 1915, July 2006, July 2007 & July 2018)
• Set monthly occurrences of high temperatures 100° or hotter: 31 days (old record 30 days in June 2013 and August 1994)

Below is an listing of yearly temperature records that were set or tied in July:

• Set consecutive days with high temperatures 100° or hotter: 46 days from June 16th to July 31st (old record 39 days from 1987, 2005 & 2013)
• Tied consecutive days with high temperatures 110° or hotter: 8 days from July 15th to 22nd (previously set in June 2021, 12th to 19th)
• Set consecutive days with low temperatures 80° or warmer: 10 days from July 7th to 16th (old record 9 days from June 2017 & July 2020)
• Set consecutive days with low temperatures 85° or warmer: 4 days from July 12th to 15th (old record 2 days from July 1915, July 2006, July 2007 & July 2018)

Although not a yearly record, the low temperature of 87° on the July 13th ranks tied as the 5th warmest low temperature overall on record.

This years Monsoon started late, possibly due to increasing El Niño conditions, which led to below normal rainfall across most of the metro area. However, there were several noteworthy severe thunderstorm days/events that produced significant wind damage across parts of the metro area along with hail and brief heavy rainfall.

• 17th: Severe thunderstorms rolled through the area between 3 PM and 6 PM producing winds gusts of 58 mph at Davis-Monthan AFB, 60 mph at Marana regional airport, 64 mph at Tucson International Airport and 67 mph near Tanque Verde and Speedway, large hail (1"), and lots of wind damage to trees, power poles and structures across parts of the foothills. Up to 5,000 TEP customers lost power.
• 23rd: A severe thunderstorm hit the southwest part of the metro area between 630 PM and 730 PM producing damage to trees, power poles and structures. Up to 9,000 TEP customers lost power.
• 28th: A very intense thunderstorm rolled through the metro area producing wind gusts up to 70 mph, large hail up to 1.5, and wind damage to trees, power poles and structures. Up to 50,000 TEP customers were without power a one time.
• 31st: A line of severe thunderstorms moved through the metro area between 530 PM and 730 PM producing wind gusts to 58 mph at Tucson International Airport and 72 mph at Marana Regional Airport. Heavy rain accompanied these storms with up to 2" of rain in spots that led to localized flash flooding.

Rainfall amounts across the metro area, using several sources like rainlog.org, the Pima County Regional Flood Control District gages and CoCoRaHS, ranged widely from a tenth of an inch to 4.00". The International Airport, which is the official recording spot in Tucson, recorded 2.00" which is below normal and ranks as the ranks as the 61st wettest on record.

Monsoon 2023 is running below below normal through the end of July with 2.00" being recorded at the Tucson International Airport. This ranks as the 63rd driest on record for the first 47 days of the monsoon. Rainfall totals across the Tucson metro area for the season so far ranged widely from a tenth of an inch to 4.00".

Coming into July, the 2023 average yearly temperature was running 1.2° below normal. After the hottest calendar month on record, the average yearly temperature stands at only one-tenth of a degree below normal.

The average yearly temperature, through the end of July, of 70.2° ranks as the 23rd warmest on record. Rainfall at the Tucson International Airport, the official location in Tucson, of 5.54" is around a half an inch above normal and ranks as the 54th wettest January through July period on record. The water year rainfall since October 1st of 7.34" is a smidge above normal and ranks as the 61st wettest water year to date with two months left in the water year calendar.

The August outlook from the Climate Prediction Center for Tucson favors above-normal monthly mean temperatures (53% above vs 14% below) and below-normal total precipitation amounts (38% below vs 29% above).

The month began with the area in a historic streak of triple-digit high temperatures that eventually ended on August 8th at 53 days when the high was 99°. The 53 days shattered the previous record of 39 days which occurred in 1987, 2005 & 2013. As this streak came to an end, Tucson recorded the first back-to-back daily low temperatures in August being 84° or warmer, highlighted by tying the warmest August low temperature on record of 85° on the 6th. The previous occurrences of an 85° low in August were well over 100 years ago on August 1, 1914, and August 1, 1902. A little over a week later, Tucson did it again with back-to-back low temperatures of 84° or warmer.

During the first seven days of the month, little if any rainfall was recorded across the metro area. That changed on the 8th when scattered showers and thunderstorms moved across the metro area. The remainder of the month had daily occurrences of thunderstorms moving across parts of the metro area. Severe thunderstorms impacted the metro area on the 16th, 18th, 21st and 22nd with the airport recording peak wind gusts of 62 mph on the 18th & 22nd.

The monthly average temperature of 89.9° is 3° ABOVE normal and ranks as the 3rd hottest August on record, behind 2020 & 1994. Temperature extremes for the month ranged from a high of 110° on the 5th to a low of 68° on the 21st. Eleven daily temperature records were set or tied during the month. Four of those were record highs while seven were record warm lows.

Rainfall amounts, using several sources like rainlog.org, the Pima County Regional Flood Control District gages, and CoCoRaHS, varied widely across the metro area which is always the case during the summer thunderstorm season. Amounts ranged from 0.50" to 3.50" with much of the city environs recording less than 1.00". The International airport, which is the official recording spot in Tucson, was one of the wetter spots in the metro area recording 2.39" which is four-tenths of an inch above normal and ranks as the 48th wettest August on record. Combined with the 2021 total of 3.85" and the 2022 total of 2.82", this is the first time since 1990-93 that three or more consecutive Augusts recorded above-normal rainfall at the official location.

Summer 2023 will go into the record books as one of the hottest on record, but it didn't start off that way. June was cooler than normal with Tucson recording its first below-normal June since 2009 and second since 1998. July saw relentless record-setting heat, thanks to a dome of high pressure over the desert southwest, which resulted in the hottest July and calendar month on record. August was cooler than July but still hot coming in as the 3rd hottest on record.

One of the biggest records that fell during the Summer of 2023 was the most consecutive days with a high temperature of 100° or hotter. On June 16th, the Tucson airport recorded the 2nd triple-digit high of the year. 52 days later, on August 7th, the last in a string of 53 consecutive days of triple-digit highs occurred. The 53 consecutive days shattered the old record of 39 days which occurred three times previously, in 1987, 2005 & 2013. Another temperature record that was established was the number of days with highs of 110° or hotter. There were 17 such days which shattered the old record of 10 days from 1990 & 1994.

The average summer mean temperature of 89.5° is 2.4° above normal and ranks as the 3rd hottest on record or two-tenths of a degree hotter than last Summer. The two hottest Summers on record are 90.0° in 2020 & 89.9° in 1994.

Temperature extremes ranged from a high of 112° on July 18th, 19th, 20th & 25th to a low of 60° on June 1st. The 69 days with highs 100° or hotter is the 3rd most for summer while the 47 days with highs 105° or hotter is also the 3rd most for summer. Daily lows were warm with Tucson establishing a new record with 6 days of lows 85° or warmer. There were 25 daily temperatures records set during Summer 2023. Fourteen were highs while eleven were for warm lows.

As is usually the case during the summer thunderstorm season rainfall amounts, using several sources like rainlog.org, the Pima County Regional Flood Control District gages, and CoCoRaHS, ranged widely from 1.00" to 4.00" with localized amounts up to 5.00". The International airport, which is the official recording spot in Tucson, recorded 4.39" which is average for Summer and ranks as the 62nd driest Summer on record.

The average yearly temperature, through the end of August, of 72.7° is three-tenths of a degree above normal and ranks as the 16th warmest on record, tied with 2013. Rainfall at the Tucson International Airport, the official location in Tucson, of 7.93" is just over eight-tenths of an inch above normal and ranks as the 50th wettest January through August period on record. The water year is above normal since October 1st at 9.73" which ranks as the 60th wettest water year to date with one month left in the water year calendar.

The September outlook from the Climate Prediction Center for Tucson favors above-normal mean temperatures (43% above vs. 24% below). It favors equal chances for either above-normal (33%) or below-normal (33%) total precipitation amounts.

Five record high temperatures set or tied

The first day of the month had scattered showers and thunderstorms rolling through the metro area with rainfall amounts generally less than a quarter of an inch. The high temperature on the first, due to considerable cloud cover, only warmed up to 87°. This was the 3rd coolest September 1st on record with 1967 (83°) and 1935 (85°) being cooler. High temperatures returned to early September norms on the 2nd through the 4th before starting an extended period of triple-digit highs from the 5th through the 11th. In this period of triple-digit highs, Tucson recorded its hottest September on record with a high of 111° on the 10th. The previous hottest September high temperature was 110° on September 4, 2020.

A weather system passing by north of the area on the 12th and 13th brought scattered showers and thunderstorms to the metro area daily totals mostly less than a quarter of an inch with isolated areas recording between 0.50" and 1.00".

The remainder of the month was dry with highs in the 90s to 104° and lows from the mid-60s to lower 70s.

The monthly average temperature of 85.7° goes into the record books as the WARMEST September on record, tied with 2020. The average monthly high temperature of 99.7° established a new monthly record, eclipsing the old record of 99.6° from 1956. Temperature extremes for the month ranged from a high of 111° on the 10th to a low of 67° on the 19th, 21st, 24th, 25th, and 30th. Five record-high temperatures were set or tied. This is the greatest number of record-high temperatures set or tied during September since 1910 when there were six records set/tied.

Rainfall amounts, using several sources like rainlog.org, the Pima County Regional Flood Control District gages, and CoCoRaHS, varied widely across the metro area with totals ranging from 0.10" to 1.25". The Tucson International Airport, which is the official recording spot in Tucson, recorded slightly over a third of an inch (0.34") which is just under 1" below normal and ranks as the 29th driest September on record, tied with 1951.

Monsoon 2023 ended up the HOTTEST on record with an average season temperature of 89.8° which is 3.5° degrees above normal. The previous hottest Monsoon was in 2020 with an average season temperature of 89.4°. Temperature extremes ranged from 112° on July 18th, 19th, 20th, and 25th to 64° on June 17th.

Rainfall amounts, using several sources like rainlog.org, the Pima County Regional Flood Control District gages, and CoCoRaHS, varied widely across the metro area as is usually the case during the summer thunderstorm season. Amounts ranged from 1.5" to 5" with localized higher amounts up to 7". The Tucson International Airport, the official recording location in Tucson, recorded 4.73" which ranks as the 39th driest monsoon on record. Click on the image to the right to see how 2023 compared to the historical record.

The average yearly temperature, through the end of September, of 74.1° is half of a degree above normal and ranks as the 14th warmest on record.

Rainfall amounts, using several sources like rainlog.org, the Pima County Regional Flood Control District gages and, CoCoRaHS, have varied widely across the metro area. Amounts ranged from 4" to 10" with localized higher amounts up to 12". The Tucson International Airport, which is the official recording spot in Tucson, has recorded 8.27" which is slightly below normal (-0.15") and ranks as the 57th driest January to September on record.

The 2022-23 water year ended up slightly drier than normal with 10.07" being reported at the airport. This ranks as the 56th driest water year period (October 1st to September 30th) on record.

The October outlook from the Climate Prediction Center for Tucson favors above-normal mean temperatures (36% above vs. 31% below) and above-normal (37% above vs 30% below) total precipitation amounts.

The month started with near-normal temperature through the 4th before strong high pressure aloft built over the desert southwest bringing well above normal and record temperatures to the area from the 5th through the 8th. The warmest October low temperature on record of 79° occurred on the 7th. This broke the previous monthly record of 77° which occurred first on October 10, 1934, and later tied on October 3, 1977.

Above-normal temperatures would continue through the 11th then cool to near normal on the 12th through the 14th. Strong high pressure aloft once again built over the desert southwest bringing another round of record or near-record high temperatures to the area from the 16th to the 22nd. Tucson would tie, at the time, the latest calendar triple-digit high date on the 16th with a high of 101°. A new latest calendar triple-digit high date would be set on the 19th (100°) and then set again a day later on the 20th with a high of 101°. 2023 also set a new record for the number of days between the first (April 30) and last (October 20) calendar triple-digit high at 172 days.

An upper air pattern change brought in cooler-than-normal temperatures by the 24th and 25th with scattered showers and thunderstorms moving across the area on the 24th. The thunderstorms on the 24th produced localized heavy rain and small hail that covered the ground across portions of the metro area.

The month finished dry with highs in the 80s on the 26th through the 28th and in the 70s on the 29th to the 31st.

The monthly average temperature of 76.5° is 3.9° ABOVE normal and ranks as the 4th warmest October on record. Temperature extremes for the month ranged from a high of 101° on the 6th, 16th & 20th to a low of 46° on the 30th. Seven daily record temperatures were set or tied during the month. Five of them were for record highs (101° on the 6th, 101° on the 16th, 100° on the 19th, 101° on the 20th & 98° on the 21st) and two were for record warm lows (79° on the 7th & 73° on the 8th). The four triple-digit highs is tied with 1917 & 1991 for the second most in October but well short of the October record of eight occurrences in 2020.

Rainfall amounts across the metro area, using several sources like rainlog.org, the Pima County Regional Flood Control District gages and CoCoRaHS, ranged widely from a trace to 1.50" with localized amounts near 2". The International airport, which is the official recording spot in Tucson, recorded just under two-tenths of an inch /0.19"/. This ranks as the 47th driest October on record, tied with 1941.

Two-thirds of climatological Fall is in the books and 2023 ranks as the warmest & 22nd driest on record with one month left to go.

The average yearly temperature, through the end of October, of 74.3° is 0.8° above normal and ranks as the 8th warmest on record, tied with 1989. The yearly rainfall total of 8.46" at the Tucson International airport, the official location in Tucson, ranks as the 47th driest January through October period on record.

The November outlook from the Climate Prediction Center for Tucson favors above-normal mean temperatures (56% above vs. 11% below). It favors equal chances for either above-normal (33%) or below-normal (33%) total precipitation amounts.

The monthly average temperature of 65.1° is 3.6° ABOVE normal and ranks as the 5th warmest November on record. Temperature extremes for the month ranged from a record-tying high of 94° on the 5th to a low of 39° on the 26th. Five daily record temperatures (2 highs & 3 warm lows) were set or tied during the month. There were four daily highs in the low to mid-90s which is tied for the third most on record to occur in November. Here's an interesting fact. The high & low temperatures on the 14th (84° & 65°), 15th (86° & 59°), & 16th (82° & 62°) are the first occurrences of those combinations that occurred in November dating back to 1894.

Rainfall amounts, using several sources like rainlog.org, the Pima County Regional Flood Control District gages, and CoCoRaHS, were mostly less than a half an inch /0.50"/ with localized totals up to eight-tenths of an inch /0.80"/. The International Airport, which is the official recording spot in Tucson, recorded just under three-tenths of an inch /0.28"/ which is below normal and ranks as the 52nd driest November on record.

The Fall outlook from the Climate Prediction Center for Tucson strongly favored above-normal seasonal mean temperatures (57% above vs 10% below) and slightly favored below-normal total precipitation amounts (35% below vs 32% above).

The combination of the warmest September, the 4th warmest October, and the 5th warmest November produced the 2nd warmest Fall season on record. The average Fall temperature of 75.8° is 3.5° above the 1991-2020 normal. The warmest Fall occurred in 2017 (76.5°). Temperature extremes for Fall ranged from a high of 111° on September 10th to a low of 39° on November 26th. 19 days recorded triple-digit high temperatures which is the 2nd most for Fall on record.

Rainfall amounts across the metro area, using several sources like rainlog.org, the Pima County Regional Flood Control District gages and CoCoRaHS, ranged widely across the metro area from 0.30" to 1.5". The International airport, which is the official recording spot in Tucson, was on the dry side as only eight-tenths of an inch /0.81"/ was recorded. This ranks as the 14th driest Fall on record.

The average yearly temperature through the end of November of 73.5° ranks as the 5th warmest on record. The yearly rainfall total of 8.74" at the Tucson International airport, the official location in Tucson, ranks as the 44th driest January through November period on record.

The Winter outlook from the Climate Prediction Center for Tucson favors equal chances for either below, near, or above normal for seasonal mean temperatures and total precipitation amounts.

The season's first winter storm impacted the area on the 22nd & 23rd with widespread valley rain and high-elevation mountain snow. The bulk of the precipitation fell on the 22nd with totals mainly between 0.50" and 1.75". The airport recorded 1.25" on the 22nd which ranks as the 4th wettest December day on record. In the wake of this system, temperatures were below normal through Christmas before warming to above normal to close out the year.

The monthly average temperature of 56.7° is 3.7° above normal and ranks as the 6th warmest December on record, tied with 2010. Temperature extremes for the month ranged from a high of 83° on the 6th to a low of 34° on the 15th. The high temperature of 80° on the 18th tied the daily record previously set in 1950. Although there were several spots in the metro area that had a morning or two with freezing low temperatures, the airport officially didn't record any for the month. This is the first December since 1977 that the airport didn't record a 32° or colder low temperature.

Rainfall amounts, using several sources like rainlog.org, the Pima County Regional Flood Control District gages, and CoCoRaHS, ranged from 0.75" to 2.00". The Tucson International Airport, the official recording spot in Tucson, recorded 1.47" which is half an inch above normal and ranks as the 31st wettest December on record.

Looking ahead into January

A strong El Niño will continue in the equatorial Pacific to start 2024. The January outlook from the Climate Prediction Center for Tucson favors below-normal monthly mean temperatures (59% below vs. 8% above) and above-normal total precipitation amounts (46% above vs. 21% below).

2023 will be remembered for the cooler-than-normal first half of the year; a record-setting consecutive day steak of triple-digit highs; another hot Summer; a below-average Monsoon; and the warmest second half of the year on record which leads to another top 10 warmest year on record. Click on the monthly tabs above for the full individual monthly text reports.