November 2017 Summary – Drier and Sunnier Than Average

Blue Hill Observatory

November 2017 Summary:

After a warm start, the November mean temperature ended near average, but the month was much drier than normal. The 24-hour mean temperature for the month of 41.7 deg F was 1.1 degrees warmer than the 120-year average for November and about a half degree cooler than the 1981-2010 30-year average. The high temperature of 74F on the 3rd was within one degree of the record high for the date. The first freeze of the season (32F or colder) occurred on the 9th, which was the fifth latest first freeze on record. The warm start to the month turned around quickly, and the coldest temperature during November of 18F on the 11th was only the fourth time in the entire Blue Hill period of record that a temperature colder than 20F occurred on November 11th or earlier, though this reading was one degree above the record for that date of 17F in 1956. A total of 2.04 inches of precipitation was measured during the month, which was more than two inches less than the long-term 120-year average and nearly three inches less than the 30-year mean. The greatest amount in 24 hours was just 0.87 inches on the 22nd. The one thunderstorm day on the 16th raised the annual total to 18. The mean wind speed for November was 13.0 mph, and the prevailing direction was from the west-northwest. A peak gust of 50 mph occurred from the west on the 19th. The month was much sunnier than average with 151.8 hours of bright sunshine, or 54 percent of possible, which was seven percent more than the long-term November mean.

BHO Latest First Freeze, 32 deg F or lower, (1885-2017):

1) Nov. 15, 1938
2) Nov. 12, 1977
3) Nov. 11, 1994
4) Nov. 10, 1956
5) Nov. 9, 2017
6) Nov. 7, 1971

Fall (Sep-Nov) 2017 Summary:

Fall 2017 was exceptionally warm until the middle of November, including the warmest October on record, and rainfall was very close to normal. The 24-hour mean temperature for Fall of 55.3 deg F was 4.3 degrees warmer than the 120-year average and 3.4 degrees warmer than the 1981-2010 30-year normal, which made this season the warmest Fall on record, surpassing 55.1 deg F in 2011. The season began wetter than average and became increasingly dry through November. The precipitation total of 13.48 inches was over an inch more than the long-term mean and just 0.05 inches drier than the 30-year mean. The Fall mean wind speed of 12.2 mph tied for the sixth lowest on record. Bright sunshine during Fall was 56 percent of possible, which was three percent more than average.

BHO Warmest Fall (Sep-Nov) 24-hour Corrected Mean Temperature, deg F (1885-2017):

1) 55.3 in 2017
2) 55.1 in 2011
3) 54.8 in 1931
   54.8 in 2015
5) 54.3 in 1946
   54.3 in 2001

Mike Iacono
Chief Scientist
Blue Hill Observatory