November 2023 Summary – Sixth Sunniest on Record

Blue Hill Observatory November 2023 Summary: 

November was cooler and drier than average with much more sunshine than expected. The approximated 24-hour mean temperature for the month of 39.7 deg F was 1.0 degree cooler than the 1891-2020 130-year average for November, and it was 2.4 degrees cooler than the 1991-2020 30-year average. The average maximum temperature of 48.5 deg F was 1.6 degrees cooler than the 30-year normal, and the average minimum temperature of 31.8 deg F was 2.0 degrees cooler than the 30-year normal. The warmest day reached 65F on the 7th, and the lowest temperature was 20F on the 25th. The total precipitation was 2.18 inches, which was 2.13 inches less than the 30-year normal. More than half of the monthly rainfall, 1.25 inches, fell within 24 hours on the 21st-22nd, and there were only eight days with measurable precipitation. A trace of frozen precipitation was observed on several days, and the total trace was 1.8 inches below normal for November. There were no thunderstorm days during the month, which was typical for the month. The mean wind speed was 11.3 mph, which was the lowest on record for November, and the prevailing wind direction was from the northwest. The highest wind gust was 46 mph from the southeast during the rainfall on the 27th. November sunshine was much above average with 174.5 hours of bright sunshine, or 62 percent of possible, which was fourteen percent more than the long-term average for the month, and November was the sixth sunniest on record.

BHO Lowest November Mean Wind Speed, mph (1885-2023):

1) 11.3 in 2023
2) 11.7 in 2021
3) 11.9 in 2016
4) 12.1 in 1992
    12.1 in 2000
6) 12.3 in 2012

BHO Highest November Sunshine, hours (1886-2023):

1) 174.5 in 2021 (67%)
2) 182.3 in 1939 (64%)
3) 181.5 in 1917 (64%)
4) 181.4 in 1976 (64%)
5) 178.5 in 2022 (63%)
6) 174.5 in 2023 (62%)
7) 173.9 in 1905 (61%)

Blue Hill Observatory Fall (September-November) 2023 Summary: 

The fall season was generally warm with less precipitation and more sunshine than expected. The approximated 24-hour mean temperature for the season of 53.5 deg F was 2.4 degree warmer than the 1891-2020 130-year average for the season. The average maximum temperature for fall of 63.2 deg F was 2.0 degrees warmer than the 30-year normal. The average minimum temperature of 46.5 deg F was 2.0 degrees warmer than the 30-year normal, and it tied as the eighth warmest on record. Daily fall temperatures ranged from a high of 92F on September 7th to a low of 20F on November 25th. The total precipitation for fall was 10.92 inches, which was 2.94 inches less than the 30-year normal. The greatest rainfall in 24 hours was 1.92 inches on September 13th, and rainfall during September included the effects of both Hurricane Lee and Tropical Storm Ophelia as they passed offshore. The mean wind speed for fall was 10.4 mph, which was the lowest on record for the season. The highest wind gust during fall was only 46 mph from the southeast on November 27th. After a less sunny than average September and a near average October, a very sunny November compensated so that fall sunshine was above average with 551.4 hours, or 57 percent of the possible bright sunshine, which was three percent more than the long-term average.

BHO Highest Fall Average Minimum Temperature, deg F (1885-2023):

1) 48.2 in 2011
2) 47.3 in 2017
3) 46.9 in 1931
4) 46.8 in 2021
5) 46.7 in 2005
   46.7 in 2015
7) 46.6 in 1946
8) 46.5 in 1961
   46.5 in 2016
   46.5 in 2023

BHO Lowest Fall Mean Wind Speed, mph (1885-2023):

1) 10.4 in 2023
2) 11.4 in 2021
3) 11.6 in 2016
4) 11.7 in 2022
5) 11.8 in 2018

Mike Iacono
Chief Scientist
Blue Hill Observatory