Spring 2025 Summary – Tied for Fourth Warmest on Record

Blue Hill Observatory Spring (Mar-May) 2025 Summary: 

Spring 2025 temperature and precipitation were well above average with much less snowfall and less sunshine than expected. The approximated 24-hour mean temperature for spring of 49.0 deg F was 4.1 degrees warmer than the 1891-2020 130-year average for the season, and it was 2.6 degrees warmer than the 1991-2020 30-year average. Spring 2025 tied as the fourth warmest on record. The average maximum temperature of 59.0 deg F was 3.3 degrees warmer than the 30-year normal, which tied as the sixth warmest on record. The average minimum temperature of 39.8 deg F was 2.1 degrees warmer than the 30-year normal, which tied as the seventh warmest on record. The warmest temperature during spring was 84F on May 3rd, and the lowest temperature was 8F on March 3rd. The mean water vapor pressure, which is an absolute measure of water vapor in the air, was the second highest on record for spring at 8.8 mb, which corresponds to a mean dew point of about 41F. This amount was above the long-term mean water vapor pressure for spring of 7.4 mb, which equals a mean dew point of about 37F. The season was wetter than average, and the total precipitation was 16.09 inches, which was 1.99 inches more than the 30-year normal. The wettest month was May with 7.62 inches, which offset the slightly below average precipitation in March and April. The greatest amount in 24 hours was 3.73 inches of rain, which included a thunderstorm and gusty winds on May 22nd-23rd. There were six thunderstorm days during spring, including one in April and five in May. The total snowfall for the season was just 1.7 inches, all occurring in April, which was 16.1 inches below the seasonal average. The lowest sea-level pressure during spring was 29.04 inches on May 31st, which tied the lowest pressure ever observed in May, and the highest sea-level pressure was 30.56 inches on April 2nd. The mean wind speed was 12.9 mph, and the prevailing wind direction was from the south-southwest. The highest wind gust was 69 mph from the south during a warm rain storm on March 6th. Spring sunshine was below average with 561.7 hours of bright sunshine, or 47 percent of possible, which was three percent less than the long-term average for the season.

BHO Warmest Spring (Mar-May) Approximated 24-Hour Mean Temperature, deg F (1885-2025):

1) 51.3 in 2010
2) 50.9 in 2012
3) 49.4 in 1991
4) 49.0 in 1977
   49.0 in 2025
6) 48.4 in 1998
   48.4 in 2022
8) 48.3 in 2023
9) 48.2 in 1976
10) 48.1 in 1945

BHO Warmest Spring (Mar-May) Average Maximum Temperature, deg F (1885-2025):

1) 61.4 in 2010
2) 61.1 in 2012
3) 60.5 in 1991
4) 60.3 in 1977
5) 59.6 in 1945
6) 59.0 in 1976
   59.0 in 2022
   59.0 in 2025
9) 58.5 in 1903
   58.5 in 1921
   58.5 in 2021

BHO Warmest Spring (Mar-May) Average Minimum Temperature, deg F (1885-2025):

1) 9.1 in 2012
2) 42.4 in 2010
3) 40.5 in 1945
4) 40.4 in 1998
   40.4 in 2024
6) 39.9 in 1973
7) 39.8 in 1991
   39.8 in 2025
9) 39.7 in 1979
   39.7 in 2023

BHO Highest Spring (Mar-May) Average Water Vapor Pressure, mb (1932-2025):

1) 9.1 in 2012
2) 8.8 in 2025
3) 8.7 in 1979
   8.7 in 2024
5) 8.6 in 1973
   8.6 in 2011

Mike Iacono
Chief Scientist
Blue Hill Observatory