Fall 2024 Summary – Fifth Warmest and Ninth Driest on Record

Blue Hill Observatory Fall (Sep-Nov) 2024 Summary: 

Fall 2024 temperature was much above average, and there was much less precipitation and much more sunshine than expected. The approximated 24-hour mean temperature for fall of 54.6 deg F was 3.5 degrees warmer than the 1891-2020 130-year average for the season, and it was 2.1 degrees warmer than the 1991-2020 30-year average. Fall 2024 was the fifth warmest on record. The average maximum temperature of 64.3 deg F was 3.2 degrees warmer than the 30-year normal, and it was the second warmest on record. The average minimum temperature of 46.4 deg F was 1.5 degrees warmer than the 30-year normal, which was the eleventh warmest on record. Fall 2024 was generally warm, though the warmest period was the 24 days from October 19th to November 11th, which included eleven days that exceeded 70F and two days that reached 80F, including the latest reading of 80F ever observed on November 6th. The warmest temperature was 82F on October 21st and the coldest temperature was 26F on November 30th. The season was much drier than average, and the total precipitation was 6.26 inches, which was 7.60 inches less than the 30-year normal. The break in the fall dry period came with a rain storm on November 21st-23rd, which brought a total of 2.53 inches. The greatest rainfall amount in 24 hours was 1.61 inches on November 21st-22nd. There were no thunderstorm days during fall, which was three less than average for the season. No snowfall was measured during the season. The mean wind speed was 11.1 mph, which was the second lowest on record for the season, and the prevailing wind direction was from the northwest. The highest wind gust was 52 mph from the west-northwest on November 24th. With a dry pattern most of the season, fall sunshine was the highest on record with 641.6 hours of bright sunshine, or 66 percent of possible, which was twelve percent more than the long-term average for the season.

BHO Warmest Fall (Sep-Nov) Approximated 24-Hour Mean Temperature, deg F (1885-2024):

1) 55.3 in 2017
2) 55.1 in 2011
3) 54.8 in 1931
   54.8 in 2015
5) 54.6 in 2024
6) 54.4 in 2020
7) 54.3 in 1946
   54.3 in 2001
   54.3 in 2022

BHO Warmest Fall (Sep-Nov) Average Maximum Temperature, deg F (1885-2024):

1) 64.8 in 1931
2) 64.3 in 2024
3) 64.2 in 1946
4) 64.1 in 2017
5) 64.0 in 1941
   64.0 in 2015
7) 63.8 in 2001
   63.8 in 2011

BHO Lowest Fall (Sep-Nov) Precipitation, inches (1886-2024):

1) 4.32 in 1946
2) 4.61 in 2001
3) 4.83 in 1952
4) 5.10 in 1941
5) 5.35 in 1916
6) 5.52 in 1931
7) 5.54 in 1914
8) 6.24 in 1887
9) 6.26 in 2024
10) 6.32 in 1915

BHO Lowest Fall (Sep-Nov) Mean Wind Speed, mph (1885-2024):

1) 10.4 in 2023
2) 11.1 in 2024
3) 11.4 in 2021
4) 11.6 in 2016
5) 11.7 in 2022

BHO Highest Fall (Sep-Nov) Bright Sunshine, hours (1886-2024):

1) 641.6 in 2024 [66%]   
2) 623.3 in 2001 [64%]   
3) 610.7 in 1941 [63%]   
4) 605.1 in 1973 [62%]   
5) 599.1 in 1966 [62%]   
6) 594.5 in 1952 [61%]   
7) 594.4 in 1998 [61%]   

Mike Iacono
Chief Scientist
Blue Hill Observatory