November 2020 Summary – Fourth Warmest on Record

Blue Hill Observatory November 2020 Summary:

November was unseasonably warm and both wetter and sunnier than average. The 24-hour adjusted mean temperature for the month of 46.9 deg F was 6.3 degrees warmer than the 120-year average for November, and it was 4.8 degrees warmer than the 1981-2010 30-year average. November was the fourth warmest on record and the warmest since 2011. The average maximum temperature of 56.3 deg F was 6.3 degrees warmer than the 30-year mean, and it was the second warmest on record. The average minimum temperature of 38.6 deg F was 3.8 degrees warmer than the 30-year mean, which tied for the seventh warmest on record. The highest temperature observed all month was 75F on the 7th, and the lowest temperature was 18F on the 19th. The warmest period during November was an eight-day period of very warm temperatures from the 5th to the 12th, which included six days with high temperatures in the low to middle 70’s. Five of these days either tied or set new daily high temperature records including 75F on the 7th, 74F on the 9th, and 73F on the 8th and 11th. The mean temperature of 66F on the 11th, being one degree warmer than 65F, was a rare cooling degree day in November, and it was the latest cooling degree day on record. The year to date for January through November tied for the third warmest on record. November precipitation totaled 5.23 inches, which was almost an inch more than the long-term 120-year average and about a half inch more than the 30-year mean. More than three inches of the monthly total fell during strong storms on the 23rd and the 30th, including the greatest precipitation in 24 hours, which was 1.77 inches on the 23rd. A thunderstorm day was also recorded on the 23rd, the only one during November. The total thunderstorm days for the year is 19, which is three fewer than average. Snowfall for the month was only a trace, which occurred on the 2nd. The mean wind speed for the month was 13.2 mph, and the prevailing wind direction was from the south-southwest. The monthly peak wind gust was 81 mph from the south-southeast during the rain storm on the 30th. This wind gust was the highest at Blue Hill since 85 mph was recorded on January 18th, 2006. It was the eighth highest wind gust in November in the last eighty years and the highest since 1963. November sunshine was well above average with 151.1 hours of bright sunshine, or 53 percent of possible, which was six percent more than the long-term average.

BHO Warmest November 24-Hour Adjusted Mean Temperature, deg F (1885-2020):

1) 47.9 in 2011
2) 47.4 in 1975
3) 47.1 in 2006
4) 46.9 in 2020
5) 46.4 in 1948
   46.4 in 1979
   46.4 in 2009

BHO Warmest November Average Maximum Temperature, deg F (1885-2020):

1) 57.0 in 2011
2) 56.3 in 2020
3) 55.8 in 1975
4) 54.9 in 1927
5) 54.8 in 2001

BHO Warmest November Average Minimum Temperature, deg F (1885-2020):

1) 40.7 in 2006
   40.7 in 2009
3) 40.4 in 2011
4) 40.2 in 1948
5) 40.1 in 1975
6) 39.3 in 1979
7) 38.6 in 2015
   38.6 in 2020

BHO November Cooling Degree Days (1885-2020):

1) 3 on Nov 2, 1950 (81/54/68)
2) 2 on Nov 7, 1938 (75/58/67)
   2 on Nov 3, 1990 (75/58/67)
4) 1 on Nov 3, 1927 (72/59/66)
   1 on Nov 1, 1956 (74/58/66)
   1 on Nov 4, 1987 (77/55/66)
   1 on Nov 4, 1990 (75/57/66)
   1 on Nov 6, 2015 (71/60/66)
   1 on Nov 11, 2020 (73/58/66)

BHO Highest November Wind Gusts, mph (1940-2020):

1) 96 mph, SSE on 3 Nov 1951
2) 94 mph, E on 25 Nov 1950
3) 90 mph, SSW on 28 Nov 1958
   90 mph, SSW on 30 Nov 1963
5) 86 mph, SSE on 29 Nov 1963
6) 83 mph, S on 10 Nov 1942
   83 mph, SW on 29 Nov 1960
8) 81 mph, SSE on 30 Nov 2020

Blue Hill Observatory Fall (September-November) 2020 Summary:

The 24-hour adjusted mean temperature for fall of 54.4 deg F was 3.4 degrees warmer than the 120-year average for Fall, and it was 2.5 degrees warmer than the 1981-2010 30-year average. Fall was the fifth warmest on record and the warmest since 2015. The average maximum temperature for fall of 63.6 deg F was 3.0 degrees warmer than the 30-year mean, and it was the eighth warmest on record. The average minimum temperature for fall of 46.3 deg F was 2.1 degrees warmer than the 30-year mean, and it was the ninth warmest on record. Fall precipitation totaled 13.59 inches, which was over an inch more than the long-term 120-year average and very close to the 30-year mean. Much of the rainfall occurred on a small number of days; there were seven calendar days during fall with an inch or more of precipitation. All of the snowfall recorded during fall, 6.5 inches, was observed on October 30th, which was a new snowfall record for the date and the second largest snowfall ever measured in October. The mean wind speed for fall of 11.9 mph tied for the third lowest on record. However, several wind events brought very high wind speeds including peak gusts to 81 mph SSE on November 30th and 76 mph S on October 7th. Fall sunshine was close to average with 53 percent of the possible bright sunshine, which was one percent less than the long-term average.

BHO Warmest Fall (Sep-Nov) 24-Hour Adjusted Mean Temperature, deg F (1885-2020):

1) 55.3 in 2017
2) 55.1 in 2011
3) 54.8 in 1931
   54.8 in 2015
5) 54.4 in 2020

BHO Lowest Fall (Sep-Nov) Mean Wind Speed, mph (1885-2020):

1) 11.6 in 2016
2) 11.8 in 2018
3) 11.9 in 2013
   11.9 in 2020
5) 12.0 in 2008
   12.0 in 2012

 

Mike Iacono
Chief Scientist
Blue Hill Observatory