CARIBOU, Maine — Above-average temperatures that began this past summer continued into September, according to forecasters from the National Weather Service in Caribou, with temperatures last month ranging from 0.5 degrees to 4 degrees above the 30-year average.
This continued a trend established in June that saw 50 days reaching 80 degrees or higher, the most so far this century, according to Mark Bloomer, meteorologist with the NWS in Caribou. The highest all time record was lodged in 1999, with 51 days of temperatures of 80 degrees or more.
In the past, a record high temperature of 92 degrees was recorded on Sept. 1, 2010, while a record low of 23 degrees occurred on Sept. 29, 1980.
Bloomer said that if not for highs of 88 degrees on Sept. 25 and Sept. 26, 2017, the high of 88 degrees at Caribou on Sept. 16 would be a record for so late in the season.
At the same time, last month had alternating spells of above and below average temperatures. The first cool snap occurred from Sept. 8-10, with frost and freezing temperatures recorded in parts of the state.
Observers noted frost in areas around Bangor on Sept. 9, and Houlton had three consecutive nights with a low of 32 degrees or below. From Sept. 23-25, temperatures fell to approximately 20 degrees Fahrenheit for three consecutive nights, and the first sub-freezing temperature came to Caribou on Sept. 24 with a daily record low of 26 degrees.
The average maximum temperature for September is 69.3 degrees, with the average minimum 45.9 degrees, according to the NWS.
Two nights recorded a low of 32 degrees or below at Caribou, which is the average number for the month.
This summer was the all-time warmest on record in the Caribou area, according to the weather service, with an average temperature of 66.3 degrees, which eclipsed the previous record of 66 degrees set during the summer of 1973.
August was the all-time warmest month at Caribou, with an average temperature of 68.9 degrees, which was 5.3 degrees above average. It broke the previous record set in August 2015, when the average temperature was 68.2 degrees. It also was the fifth warmest month in Bangor and Millinocket, and the eighth warmest at Houlton.
The record-setting August came on the heels of the all-time warmest July registered at Caribou.
Rainfall this month was “well below average,” ranging from 40 to 70 percent of normal. At Caribou, 1.74 inches of rain was recorded, which made it the driest September since 2000 and the eighth driest on record.
The record for the most September rainfall, 8.81 inches, occurred in 1999. The least amount, 0.86 inches, fell in 1968. The most rainfall in a 24-hour period last month, 0.76 inches, fell on Sept. 26.
By late in the month, the U.S. Drought Monitor had much of Aroostook, Washington, Hancock and southern Penobscot Counties as abnormally dry with an area of moderate drought in parts of coastal Hancock County and across the southern quarter to third of Washington County.
River flows were very low at the end of last month and in most areas were less than 50 percent of normal.
