Summer 2024 Summary – Seventh Warmest on Record
Towering cumulus with anvil and rain shower passing northwest of Boston as viewed from Great Blue Hill on the afternoon of 1 July 2024. Photograph by Chief Observer Matt Douglas.
Blue Hill Observatory Summer (Jun-Aug) 2024 Summary:
Summer 2024 temperature was much above average, and there was less precipitation and more sunshine than expected. The approximated 24-hour mean temperature for summer of 70.7 deg F was 3.2 degrees warmer than the 1891-2020 130-year average for the season, and it was 1.5 degrees warmer than the 1991-2020 30-year average. Summer 2024 was the seventh warmest on record. The average maximum temperature of 81.0 deg F was 1.9 degrees warmer than the 30-year normal, and it was the seventh warmest on record. The average minimum temperature of 62.3 deg F was 1.0 degrees warmer than the 30-year normal, which tied as the sixth warmest on record. There were two three-day heat waves during summer 2024, on June 18th-20th and on August 1st-3rd, and there were ten ninety-degree days, which was four more than average. Summer 2024 was generally warm, though much of August was close to average. The warmest temperature during summer was 94F on June 20th and August 2nd, and the lowest temperature was 51F on June 16th and August 21st. The average water vapor pressure was 19.7 mb, which corresponds to a mean dew point of 63F, and this was the second highest on record since 1932. The long-term average vapor pressure for summer is 17.6 mb, which corresponds to an average dew point of 60F. The season was drier than average, and the total precipitation was 10.39 inches, which was 1.62 inches less than the 30-year normal. The wettest month was June with 4.86 inches. The largest storm and the greatest amount in 24 hours was 1.83 inches during periods of several thunderstorms on June 26th-27th. The effects of former Hurricane Debby passed far inland on August 9th-10th and brought a storm total of 0.85 inches of rainfall and a peak wind gust to 50 mph. There were fourteen thunderstorm days during summer, which is average for the season. The mean wind speed was 10.0 mph, which tied as the second lowest on record for the season, and the prevailing wind direction was from the south-southwest. The highest wind gust was 50 mph from the northwest on June 14th and 50 mph from the south-southwest on August 9th. Summer sunshine was above average with 786.3 hours of bright sunshine, or 61 percent of possible, which was four percent more than the long-term average for the season.
BHO Warmest Summer (Jun-Aug) Approximated 24-Hour Mean Temperature, deg F (1885-2024):
1) 71.6 in 2016
2) 71.5 in 2022
3) 71.3 in 2010
4) 71.1 in 2020
5) 70.9 in 2018
6) 70.8 in 1949
7) 70.7 in 2024
8) 70.6 in 1999
9) 70.4 in 1952
BHO Warmest Summer (Jun-Aug) Average Maximum Temperature, deg F (1885-2024):
1) 83.0 in 1949
2) 82.9 in 2022
3) 82.4 in 2016
4) 82.1 in 2010
5) 81.5 in 1952
6) 81.3 in 2020
7) 81.0 in 2024
8) 80.9 in 1999
80.9 in 2005
BHO Warmest Summer (Jun-Aug) Average Minimum Temperature, deg F (1885-2024):
1) 63.1 in 2020
2) 62.6 in 2022
3) 62.5 in 2010
4) 62.4 in 2018
62.4 in 2021
6) 62.3 in 2016
62.3 in 2024
8) 62.1 in 1999
62.1 in 1973
BHO Highest Summer (Jun-Aug) Average Water Vapor Pressure, mb (1932-2024):
1) 19.9 in 2021
2) 19.7 in 2024
3) 19.6 in 1973
4) 19.5 in 2018
5) 19.4 in 2013
19.4 in 2020
19.4 in 2023
8) 19.3 in 1994
BHO Lowest Summer (Jun-Aug) Mean Wind Speed, mph (1885-2024):
1) 9.5 in 2023
2) 10.0 in 2019
10.0 in 2021
10.0 in 2024
5) 10.1 in 2020
6) 10.2 in 2012
7) 10.3 in 2008
10.3 in 2009
Mike Iacono
Chief Scientist
Blue Hill Observatory
