Pacific Storm Impacting Hawaii; Atmospheric River Brings Precipitation to the Pacific Northwest and Northern California

A strong weather system will bring the potential for flash flooding, severe thunderstorms, strong to locally damaging non-thunderstorm winds, and high elevation snow to the Hawaiian Islands. Precipitation will overspread most of the eastern third of the country. A prolonged atmospheric river will bring low elevation rain and mountain snow to the Pacific Northwest and California into the Rockies. Read More >

Riverton Climate Summary Banner

Temperatures |Precipitation| Snowfall

...Highlights of 2015...

Annual - ...7th Warmest Year on Record (1918-2015), 122 percent of normal precipitation, 130 percent of normal annual snowfall and the 15th snowiest year on record.
Latest First Freeze: October 12, 2015
Monthly Temperatures: Warmest September, 2nd Warmest October, 5th Warmest June (over last 97 years, period of record 1918-2015).
Montly Precipitation: 2nd Wettest February, 9th Wettest May, 7th Wettest November
Montly Snowfall: 2nd Snowiest February and November.

Temperature Banner

Element	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	2015
Average High	29.4	39.3	50.8	59.8	62.6	83.8	84.4	85.7	81.7	66.0	42.9	28.8	59.6
Mean High (1981-2010 Normals)	31.0	37.4	49.6	60.3	69.2	79.4	88.2	86.7	74.9	60.0	43.1	29.5	59.1
Average Low	9.8	17.2	23.8	32.5	41.1	53.0	53.2	52.2	45.6	37.4	16.1	5.1	32.3
Mean Low (1981-2010 Normals)	6.2	11.0	22.5	30.6	40.1	48.1	54.0	51.4	41.4	30.0	17.6	5.4	29.9
Average Temperature	19.6	28.3	37.3	46.2	51.9	68.4	68.8	69.0	63.7	51.7	29.5	17.0	46.0
Mean Average Temperature (1981-2010 Normals)	18.6	24.2	36.1	45.4	54.6	63.8	71.1	69.0	58.2	45.0	30.3	17.4	44.5
Departure from Normal	1.0	4.1	1.2	0.8	-2.7	4.6	-2.3	0.0	5.5	6.7	-0.8	- 0.4	1.5
Rank - Coldest to Warmest 97 years of record (P.O.R 1918-2015)	66	79	78	68	26	90	20	62	97	96	51	41	85
Highest Daily Maximum	51	60	75	79	79	95	96	97	91	84	67	55	97
Date of Occurrence	18	13	28	29	30	27	4	14	1,2,13	10	1,3	9	8/14
Lowest Daily Minimum	-21	-17	-17	18	28	45	42	36	36	24	-8	-14	-21
Date of Occurrence	1	23	4	3	11	2	29	23	18	28,29	21	28	1/1
Number of Days with:
Maximum >= 90°	0	0	0	0	0	7	8	13	3	0	0	0	31
Maximum <= 32°	16	11	6	0	0	0	0	0	0	0	7	17	57
Minimum <= 32°	31	28	22	14	1	0	0	0	0	9	28	31	164
Minimum <= 0°	5	2	2	0	0	0	0	0	0	0	5	9	23
Record Highs Set or Tied	0	1	0	0	0	0	0	0	2	1	0	0	4
Record Lows Set or Tied	0	0	1	0	0	0	0	0	0	0	0	0	1

Temperature Ranks and Records:

Daily Records:

Max:

February: 60 on the 13th (tie).

September: 91 on the 13^{th (tie)}, 89 on the 26^th (tie).
October: 84 on the 10th.

Record High So Early in the Season: None

Min:

March: -17 on the 4^th.

Record Lows So Early in the Season: None

Warmest Months of September on Record
Rank	Year	Average Temperature °F
1	2015	63.7
2	1998	63.5
3	1990	63.4
4	2009, 2001	62.3
6	1938	62.2
7	1948	62.1
8	1940	62.0

Warmest Months of October on Record
Rank	Year	Average Temperature °F
1	1963	52.0
2	2015	51.7
3	2010	50.9
4	2003	50.7
5	2014	50.4
7	1988	50.0
8	1934	49.6

Top Ten Warmest Years on Record
Rank	Year	Average Temperature °F
1	2012	48.6
2	2006	47.1
3	1934	47.0
4	2007	46.5
5	2005	46.4
6	1954	46.2
7	2015	46.0
8	1953	45.9
9	2003	45.8
10	1946	45.6

Top Ten Coldest Years on Record
Rank	Year	Average Temperature °F
1	1993	39.0
2	1924	39.6
3	1984, 1944	39.7
5	1968	40.5
6	1929	40.7
7	1932	41.0
8	1983, 1923	41.5
10	1942	41.6
85	2015	46.0


Average Annual Temperature for Period of Record - Click on Graph to Enlarge

Precipitation Banner

Element	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Total (inches)	0.04	1.28	0.47	1.10	4.03	0.82	0.81	0.17	0.10	0.38	0.99	0.09	10.28
Mean Precip (1981-2010 Normals)	0.28	0.33	0.56	0.98	1.45	1.21	0.78	0.50	0.83	0.85	0.41	0.24	8.42
Departure from Normal	-0.24	0.95	-0.09	0.12	2.58	-0.39	0.03	-0.33	-0.73	-0.47	0.58	-0.15	1.86
Percent of Normal	14	388	84	112	278	68	104	34	12	45	241	38	122
Rank - Driest to Wettest 97 years (P.O.R 1918 - 2015)	20	95	59	62	89	42	64	29	13	32	91	26	78
Greatest 24-HR Total	0.02	0.55	0.31	0.58	0.95	0.32	0.35	0.09	0.08	0.34	0.32	0.05	0.95
Dates of Occurrence	12	16	3	26	20	16	8	4	4	3	26	15	5/20
Number of Days with:
Precipitation >= 0.01	3	6	4	6	17	6	5	4	3	3	7	3	67
Precipitation >= 0.10	0	3	2	4	7	4	3	0	0	1	3	0	27
Precipitation >= 1.00	0	0	0	0	0	0	0	0	0	0	0	0	0
Daily Precipitaton Records Set or Tied	0	1	0	0	1	0	0	0	0	0	0	0	2

Precipitation Ranks and Records:

One Day Precipitation Records:

February: 0.55 on the 16^th
May: 0.92 on the 25^th.

    Wettest Months of February on Record

Rank Year Precipitation (inches)

1 2004 1.33

2 2015 1.28

3 2003 0.97

4 1986 0.90

5 1955 0.86

6 1935 0.80

   Wettest Months of May on Record

Rank Year Precpitation (inches)

1 1921 6.22

2 2011 5.29

3 2008 4.75

4 1924 4.59

5 1978 4.44

6 1971 4.42

7 1908 4.28

8 1957 4.19

9 2015 4.03

10 1942 3.98

    Wettest Months of November on Record

Rank Year Precipitation (inches)

1 1996 2.13

2 1983 1.57

3 1942 1.36

4 1985 1.06

6 1945 1.04

7 2015, 1919 0.99

9 1972 0.97

10 1938, 1928 0.93

   Top Ten Driest Years on Record

Rank Year Precpitation (inches)

1 1988 3.75

2 2012 3.98

3 1974 4.12

4 1954 4.85

5 2001, 2006 5.07

7 1966 5.66

8 1990 5.71

9 1922 5.91

10 1932 6.05

78 2015 10.28

   Top Ten Wettest Years on Record

Rank Year Precipitation (inches)

1 1912 24.63

2 1923 18.43

3 1941 14.74

4 1993 13.49

5 1995 13.41

6 1998 13.39

7 1971 13.11

8 1997 12.67

9 1947 12.45

10 1944 12.19

22 2015 10.28


Annual Precipitation for Period of Record - Click on Graph to Enlarge

Snow Banner

Element	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Total (inches)	0.7	17.8	6.6	1.8	T	0.0	0.0	0.0	0.0	0.0	19.0	2.4	48.3
Mean Snowfall (1981-2010 Normals)	4.8	6.0	5.9	6.1	1.2	0.0	0.0	0.0	0.3	3.7	4.3	4.8	37.1
Departure from Normal	-4.1	11.8	0.7	-4.3	-1.2	0.0	0.0	0.0	-0.3	-3.7	14.7	-2.4	11.2
Percent of Normal	15	297	112	30	0	0	0	0	0	0	442	50	130
Rank - Least Snowiest to Snowiest 97 Years (P.O.R 1918-2015)	17	92	63	38	66*	NA	NA	NA	1^	1#	94	31	76
Greatest 24-HR Total	0.3	6.1	5.0	1.3	T	0.0	0.0	0.0	0.0	0.0	7.8	1.4	7.8
Dates of Occurrence	12	16	3	16	11	NA	NA	NA	NA	NA	26	15	11/26
Number of Days with:
Snowfall >= 1.0 inch	0	6	2	1	0	0	0	0	0	0	6	1	16
Daily Snowfall Records Set or Tied	0	2	0	0	0	0	0	0	0	0	0	01	2
* 65 Months of May on record with no snow, 2012 and 2015 only two years with a trace of snow. ^ 80 Months of September on record with no snow. # 40 months of October on record with no snow.

Snowfall Ranks and Records:

One Day Snowfall Records (inches):

February: 4.2 on the 4th, 6.1 on the 16th

Snowiest Months of February on Record
Rank	Year	Snowfall (inches)
1	1987	22.5
2	2015	17.8
3	2004	16.9
4	1959	16.0
5	2003	15.3
7	1965	13.5
8	1935, 1920	13.0
10	2011	12.8

Snowiest Months of November on Record
Rank	Year	Snowfall (inches)
1	1983	22.0
2	2015,1942	19.0
4	1920	17.0
5	1985	15.2
6	1978	14.8
7	1938, 1919	14.0
9	1967	13.5
10	1928	13.0

Top Ten Snowiest Years on Record
Rank	Year	Snowfall (inches)
1	1920	77.0
2	2013	70.6
3	2009	62.5
4	2010	60.1
5	1919	58.0
6	1923	56.2
7	1944	55.4
8	1987	53.5
9	1972	53.4
10	1942	52.5
15	2015	48.3



Annual and Seasonal Snowfall for Period of Record - Click on Graph to Enlarge

Learn more about the National Weather Service's efforts to build a Weather-Ready Nation!

Follow us on Twitter

Follow us on Facebook

Follow us on YouTube

RIW RSS Feed

Wettest Months of February on Record
Rank	Year	Precipitation (inches)
1	2004	1.33
2	2015	1.28
3	2003	0.97
4	1986	0.90
5	1955	0.86
6	1935	0.80

Wettest Months of May on Record
Rank	Year	Precpitation (inches)
1	1921	6.22
2	2011	5.29
3	2008	4.75
4	1924	4.59
5	1978	4.44
6	1971	4.42
7	1908	4.28
8	1957	4.19
9	2015	4.03
10	1942	3.98

Wettest Months of November on Record
Rank	Year	Precipitation (inches)
1	1996	2.13
2	1983	1.57
3	1942	1.36
4	1985	1.06
6	1945	1.04
7	2015, 1919	0.99
9	1972	0.97
10	1938, 1928	0.93

Top Ten Driest Years on Record
Rank	Year	Precpitation (inches)
1	1988	3.75
2	2012	3.98
3	1974	4.12
4	1954	4.85
5	2001, 2006	5.07
7	1966	5.66
8	1990	5.71
9	1922	5.91
10	1932	6.05
78	2015	10.28

Top Ten Wettest Years on Record
Rank	Year	Precipitation (inches)
1	1912	24.63
2	1923	18.43
3	1941	14.74
4	1993	13.49
5	1995	13.41
6	1998	13.39
7	1971	13.11
8	1997	12.67
9	1947	12.45
10	1944	12.19
22	2015	10.28

Pacific Storm Impacting Hawaii; Atmospheric River Brings Precipitation to the Pacific Northwest and Northern California

Riverton 2015 Annual Climate Summary