September 2024 Climate Summary for Northern and Eastern Maine

...Northern and Eastern Maine September 2024 Climate Narrative...

September 2024 was significantly warmer and much drier than

average across all of Northern and Eastern Maine.

Temperatures across the region ranged from 1.0 to 2.0 degrees

above normal over Downeast areas upwards to 2.5 to 3.5 degrees

above normal over Central/Northern areas. This made September

2024 the 5th warmest on record for Caribou and Millinocket and

6th warmest at Houlton. The month began on a relatively cool note

through the first 11 days, but then dramatically warmed mid month

especially the 16th-19th with most low terrain locations inland

from the immediate coast well into the 80s. Temperatures returned

closer to normal for the remainder of the month. Coolest morning

lows reached mid to upper 30s at a few of the cooler northern

valley sites on the 4th, 8th, 10th, 15th, 24th, and 25th with no

documented freezes or widespread killing frosts.

At the conclusion of September, the total 2024 warm season tally

of 80+ degree high temperature days amongst the climate sites

ranged from 46 at Houlton upwards to 57 at Millinocket. The total

of 49 at Caribou was the 4th greatest, while 57 at Millinocket was

7th greatest, and 46 at Houlton was the 12th greatest. The total

of 56 at Bangor did not make the top 15, with the greatest number

80+ degree high temperature days there being 87, recorded in the

dust bowl warm season years of 1930 and 1937.

Perhaps the most noteworthy aspect of the month was how dry it was

across the region, with only 25 to 35 percent of normal September

rainfall recorded except locally upwards to 50 to 60 percent of

normal over the far northwest. Blocking upper level high pressure

prevailing especially mid to late month mostly prevented moisture

laden low pressure and frontal systems from affecting the area.

The exception was the system on the 26th which resulted from 0.50

to 1.00 inch of rainfall at the climate sites and upwards to 2.00

inches over the far northwest, preventing September 2024 being the

driest of record. Even so, it was the 2nd driest of record at

Caribou, with only the 0.83 inch total of 1968 slimly drier. At

Millinocket and Houlton it was 4th driest (with Houlton tying

September 2016) and 13th driest at Bangor.

Evaporation, as measured at Caribou, far exceeded rainfall this

month with the rainfall/evaporation deficit resulting in lawns

turning brown by late in the month over Central and Downeast

areas and shallow water well levels with as low as 15th

percentile ground water levels. Other impacts include much

diminished stream and river flows to below to much below normal

across all of the region. By end of the month, the Drought Monitor

rated Northeast and Central areas as abnormally dry with moderate

drought rated over some Downeast areas.

The Outlook from the Climate Prediction Center for the month of

October is calling for somewhat greater odds of above normal

over near or below normal temperatures and equal chances of below,

near normal, or above normal precipitation. Average temperature

range from lows/highs of mid to upper 30s/mid 50s across the North

to upper 30s to around 40/around 60 across Downeast areas. Average

total precipitation ranges from 3.50 inches over the Northeast

upwards to 4.50 inches over Central/Downeast areas. Accumulating

snowfall is observed upwards to half of all Octobers across low

terrain locations across the north where the average is 1 to 2

inches with lesser amounts and frequency over low terrain Central

locations to only a trace over Downeast areas. Significant

snowfall in October is most likely over very high terrain of the

Northwest and Central mountains of the region.

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VJN/JS/CB/NCs