September 2015 Climate Summary for Northern and Eastern Maine

...Northern and eastern Maine monthly climate narrative...

September 2015 finished very close to the warmest on record, especially across the north and central and nearly the wettest on record, especially across central and Downeast Maine.

Unusually warm late summer weather continued across the region from August, with September averaging 5 to 7 degrees above normal for the month. At Caribou...Houlton and Bangor...September 2015 finished as the 2nd...3rd and 3rd warmest respectfully just behind 1999 for Caribou...1961 and 1999 for Houlton and 1961 and 1934 for Bangor. The greatest positive temperature anomalies occurred between the 5th and 10th and again between the 15th and 19th where many 80+ maximum temperatures were recorded and a couple of locations near 90 on the 7th.

The combo August and September average of 64.9 and 64.0 degrees at Caribou and Houlton this year was by far the warmest recorded exceeding the prior records of 62.5 at Caribou in 2012 and 63.0 degrees at Houlton in 1999. At Bangor...Which has a longer record...the average of 67.4 was a tie for third, finishing behind the record
of 69.4 degrees set in 1937. Continued warmth through much of September resulted in a delay of fall deciduous tree colors by one to two weeks from average dates across the region.

The rainfall character for the vast majority of the month across the region was relatively dry until the very end of the month when a slow moving cold front associated with deep tropical moisture resulted in heavy rain north beginning late on the 29th and continuing through the 30th, and excessive rainfall central and Downeast. Rainfall totals for month ranged from about average across the extreme north to about 250+ percent of average over portions of central and Downeast maine.

At Houlton, the daily total rainfall of 4.97 inches on the 30th was both the second wettest calendar day for September and for the entire calendar year...With only 5.20 inches recorded on September 11th 1954 greater. At Bangor, the daily total rainfall of 5.27 Inches on the 30th was also the second wettest september calendar day, with 5.98 inches the wettest September day again on September 11th 1954, and the third wettest calendar day of any month on record behind 6.40 inches recorded on December 14th 1927. Significant flooding occurred over portions of central and Downeast Maine on the afternoon and evening of the 30th as a result of the
Heavy to torrential rainfall.

For the entire month, the total of 10.20 inches at Houlton was the wettest september on record there, exceeding the prior September record of 9.86 inches recorded in 1967 and third among all time wettest calendar months of any name, with 11.51 inches recorded in June of 2012 the wettest. At Bangor, the total of 6.89 inches for
September 2015 finished 7th wettest, significantly behind the wettest September of record of 9.90 inches recorded in 1999.

The outlook from the Climate Prediction Center for the month of October calls for an increased likelihood of above normal temperatures across northern and eastern Maine. There is also an Increased chance of above normal precipitation across Downeast and central Maine.

The average temperatures drop rapidly during the month of October. At Caribou (Bangor), the average highs fall from 59 (64) on the 1st To 45 (52) by the end of the month. The average lows at Caribou (Bangor) fall from 39 (42) to 30 (33) by months end. Over one and one half hours of available daylight is lost during the month.