2023 Annual Climate Review for Northern and Eastern Maine

...2023 Annual Climate Review for northern and eastern Maine...

2023 was a warm and wet year across northern and eastern Maine. It
ranked as the 3rd warmest year on record at Caribou, Houlton,
Millinocket, and Bangor.  Precipitation was more variable, but
ranged from 100 to 110 percent of normal across far northern Maine
and from 110 to 125 percent of normal Downeast, and from 120 to 150
of normal across the Central Highlands.  There was lack of arctic
air in 2023 with only 22 nights below zero in Caribou when the long
term average is 38. In Bangor, there were only 10 nights with a low
below zero which was half of normal.  There also was not a lot of
extreme heat with four days with a high of 90F or warmer in Caribou
which compares to a long term average of two.  In Bangor, there were
five 90F days, which compares to an average of six.

January was much warmer than average with temperatures that averaged
from 7 to 9 degrees (F) above the 1991-2020 climate normals. There
was above average precipitation and snowfall. It ranked as the 4th
warmest January on record in Caribou and the 2nd warmest at Houlton,
Millinocket, and Bangor. A total of 38 inches of snow was observed
in Caribou and 29.3 at Bangor. In addition to the snowfall, a storm
on the 16th produced from 2 to 4 inches of sleet across the region.

Temperatures in February were much closer to average with
alternating spells of above and below average temperatures.
Precipitation was below average as was snowfall. The only exception
was from Caribou/Presque Isle north where snowfall was a bit above
average.  The most significant event of the month occurred on the
3rd into the 4th when wind chills lower than 40 below were observed
across all the region, and as low as 61 below at Frenchville, which
was the lowest wind chill since weather observations began in 1996.
The lowest wind chill in Caribou of -52F was the lowest since the
1980s, and the wind chill in Bangor of -47F was the lowest since
2005. There was also extensive blowing and drifting snow, especially
across Aroostook County and Cryoseisms/frost quakes were reported in
several locations.

March was warmer than average with above average snowfall.
Temperatures over the course of the month averaged from 2.5 to 4
degrees above average with a lack of any arctic air. There were only
4 nights with a low below zero in Caribou and no sub-zero nights in
Bangor, which is unusual. By the end of the month the snow depth
ranged from 18 to 44 inches across Aroostook County with the highest
amounts across the higher terrain west of Caribou. There was 3
inches of snow on the ground in Millinocket with little/no snow in
Bangor and along the coast.

April brought another month with above average temperatures.
Although the month began on a cool note, most days from the 10th on
had above average temperatures. For the month as a whole,
temperatures averaged from 1.5 to 3 degrees (F) above average. Total
precipitation was well below average for the month, and nearly all
of the snow that was observed occurred during the first week of the
month. The ice went out on the northern rivers around mid-month and
overall was benign with only local flooding of typical low spots
that flood most years around Fort Fairfield.  By the end of the
month, only the higher elevations of northwest Maine had any snow on
the ground with 6 to 12 inches in the tree sheltered woods.

May featured temperatures that were near to slightly below average
with a little below average precipitation. Most areas experienced
their lowest temperatures of the month (around freezing) on the 18th
or the 23rd. The warmest temperatures in the upper 80s and low 90s
were observed on the last day of the month for low elevation sites
inland from the Downeast coast. The last snow flurries of the season
were observed during a cold and blustery day on the 17th. Total
evaporation for the month was close to twice the total rainfall
meaning that there was significant drying from the typical mud
season (snow melt and frost melt) from April.

June was a cool and wet month across the region with temperatures
that averaged from 0.5 to 2 degrees below average. The warmest day
the entire month was observed the  1st with record high temperatures
in the low to mid 90s for most low elevation inland locations.  The
month was very wet with rainfall ranging from 130 to 200 percent of
normal, and locally higher. The only locations with below average
rainfall were in Caribou and Bar Harbor. There was a lack of severe
weather with no reports of severe thunderstorms the entire month.
The total monthly evaporation of 3.88 inches in Caribou was far
exceeded by the rainfall in most of the area resulting in muddy and
soft grassy areas and high streamflows, especially over central and
western sections of the area.

July was a warm and humid month across northern and eastern Maine
with above average precipitation.  Temperatures ranged from 3 to 5
degrees (F) above average and it was the all-time warmest July and
month on record in Caribou.  It ranked as the 2nd warmest July on
record in Houlton and Millinocket, and the 4th warmest in Bangor.
The key to the warmth was very mild nights across the region with a
persistent south to southwest flow and no significant cold frontal
passages until late in the month.  Rainfall at the long term climate
sites ranged from 90 to 140 percent of normal, but locally up to 200
percent across some east central locations. Total evaporation at
Caribou was greater than the rainfall at most locations meaning that
soils in many areas did dry out a bit.

August was cooler and wetter than average. Temperatures averaged
from 1 to 2.5 degrees (F) below average and there were no 80 degree
days all month in Caribou. Rainfall was well above average and
ranged from 150 to 200 percent of normal. Total evaporation in
Caribou was well below the rainfall across the region and soils
became increasingly moist.  By the end of the month there were some
fields with patches of standing water and streamflows were above to
well above average.  Although there were not a ton of reports of
severe thunderstorms, August had the most reports of any month this
year with many reports of large hail and downed trees on the 13th in
Aroostook, Penobscot, and Piscataquis Counties.

September was much warmer than normal with above normal
precipitation across most of the region. Temperatures averaged from
3.5 to 4.5 degrees (F) above average and it ranked as the 4th
warmest September on record in Caribou and tied with 1933 as the 6th
warmest in Bangor. The most significant event of the month was the
rain and wind associated with post-tropical cyclone Lee which made
landfall in Nova Scotia.  Rainfall amounts were highest along the
coast with the greatest report of 6.25 inches near Whiting in
Washington County. The highest observed wind gust was also observed
in Washington County at 83 mph near Perry.

October was much warmer than normal and temperatures averaged from 6-
7 degrees (F) above average.  It was the 2nd warmest October on
record in Caribou, Millinocket and Bangor; and tied with 2017 as the
warmest October on record in Houlton.  The warmth was very
persistent with above average temperatures every day from the 1st
through the 23rd at Caribou with only one day with below average
temperatures in Bangor from the 1st through the 28th.  The first sub-
freezing temperatures were not observed until late in the month and
close to the latest on record, except in Houlton where it was the
latest on record. The first snow of the season was observed on the
30th with amounts mostly ranging from 2 to 4 inches from northern
Washington County and southern Piscataquis County north to the Saint
John Valley. Fall foliage this year peaked during the first week of
the month in the north and by the middle of the month Downeast.

November was colder than average with below average precipitation.
Snowfall was below average Downeast and near average across central
and northern areas. Temperatures ranged from 1.5 to 3 degrees (F)
below average. The most significant events occurred on the 22nd and
27th. The storm on the 22nd produced the first measurable snow in
Bangor with an inch of snow. The heaviest snow of 6 to 10 inches was
observed from the central highlands to southeast Aroostook County.
The event on the 27th produced 1 to 4 inches of snow from Caribou
north and up to 7 inches in western Aroostook and northern Somerset
Counties.  A wind gust to 60 mph was observed in Bangor and to 66
mph at Blue Hill in Hancock County.

December was much warmer than normal and temperatures averages from
5.5 to 7 degrees above average.  It was the 2nd warmest December on
record in Caribou and Houlton, tied for the 3rd warmest in
Millinocket, and was the 4th warmest on record in Bangor.
Precipitation varied from around 90 percent of normal in the
northeast and 200 percent of normal across the southwest. Snowfall
was well below average and it was the first Christmas with no snow
on the ground in Caribou since 2010. Only 9.9 inches of snow was
observed in Caribou all month, which tied with 1947 for the 9th
least snowy December on record.  The most significant event of the
month was a storm on the 18th that produced upwards of 5 inches of
rain over the central highlands and knocked out power to nearly half
of the state. The wind gusted to 70 mph in Bangor with a wind gust
to 93 mph in Trescott in Washington County.

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