April 2025 Summary – Seventh Warmest on Record

Sunrise with distant dense cirrus clouds as viewed from Great Blue Hill on the morning of April 17, 2025. Photo by Chief Observer Matt Douglas.

Blue Hill Observatory April 2025 Summary:

April 2025 was much warmer than average with below average precipitation and snowfall. The approximated 24-hour mean temperature for the month of 49.3 deg F was 4.4 degrees warmer than the 1891-2020 130-year average for April, and it was 2.6 degrees warmer than the 1991-2020 30-year average. April 2025 was the seventh warmest on record. The average maximum temperature of 59.6 deg F, which was 3.3 degrees warmer than the 30-year normal, tied as the tenth warmest on record. The average minimum temperature of 38.9 deg F was 1.0 degrees warmer than the 30-year normal. After a relatively cool start, the second half of April was warmer and included only three days cooler than average. The warmest temperature during April was 82F on the 19th, and the coldest temperature was 24F on the 9th. The final freeze of the season was 31F on April 11th. The mean water vapor pressure, which is an absolute measure of water vapor in the air, was 7.4 mb, which corresponds to a mean dew point of about 37F. This amount was above the long-term mean water vapor pressure for April of 6.7 mb, which equals a mean dew point of about 34F. The total precipitation was 3.41 inches, which was 1.35 inches less than the 30-year normal. The largest storm of the month brought a mixture of rain and snow and a total of 0.74 inches of liquid equivalent precipitation, including 0.6 inches of snow, on the 11th-13th, and the greatest amount in 24 hours was 0.54 inches on the 11th-12th. Due to the persistent dry weather this year, which has brought about 75 percent of the 30-year normal precipitation, the area is beginning to experience abnormally dry to moderate drought conditions as of the end of April. Total snowfall was 1.7 inches, which was 1.1 inches below average. There was one thunderstorm day during April on the 15th. The minimum sea-level pressure at Blue Hill during April was 29.29 inches on the 15th, and the maximum sea-level pressure was 30.56 inches on April 2nd. The mean wind speed was 13.2 mph, and the prevailing wind direction was from the west-northwest. The highest wind gust was 53 mph from the northwest on the 15th and the 20th. April bright sunshine was above average with 201.2 hours, or 52 percent of possible, which was three percent more than the long-term average for the month.

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

1) 51.5 in 2010
2) 51.0 in 1976
3) 50.1 in 2017
4) 49.9 in 2012
5) 49.4 in 1945
49.4 in 2023
7) 49.3 in 2025
8) 49.0 in 1994

BHO Warmest April Average Maximum Temperature, deg F (1885-2025):

1) 62.4 in 1976
2) 62.2 in 2010
3) 61.8 in 2012
4) 61.2 in 1945
5) 60.6 in 2017
6) 60.4 in 1941
7) 60.3 in 1991
8) 59.8 in 2005
   59.8 in 2023
10) 59.6 in 1969
   59.6 in 2025

Mike Iacono
Chief Scientist
Blue Hill Observatory