April 2023 Summary – Fifth Warmest on Record

Blue Hill Observatory April 2023 Summary: 

April 2023 was much warmer than average with below average precipitation and snowfall. The approximated 24-hour mean temperature for the month of 49.4 deg F was 4.5 degrees warmer than the 1891-2020 130-year average for April, and it was 2.7 degrees warmer than the 1991-2020 30-year average. April 2023 tied with 1945 as the fifth warmest on record, and it was the warmest since 2017. The average maximum temperature of 59.8 deg F, which was 3.5 degrees warmer than the 30-year normal, tied as the eighth warmest on record. The average minimum temperature of 40.9 deg F was 3.0 degrees warmer than the 30-year normal, and this mean was the fourth warmest on record. Much of the month was near average for temperature, with most of the excess warmth occurring during a five day period from the 11th to 15th, which included two days in the middle 70’s and two days that reached the upper 80’s. The warmest temperature during April was a tie with 88F on the 13th, which surpassed the previous record for the date of 85F in 1945, and 88F on the 14th, which broke the previous record for this date of 80F in 1945. The total precipitation was 3.59 inches, which was 1.17 inches less than the 30-year normal. The largest storm of the month was a major inland cutoff low over the Northeastern US, which brought a total of 1.91 inches of rain on the 29th and 30th, and the greatest rainfall in 24 hours during April was 1.72 inches on the 30th. The persistent cool, cloudy, and showery weather caused by this storm continued into early May. The minimum sea-level pressure at Blue Hill during April was 29.18 inches at the very end of the day on the 30th. There was no snowfall during April, which was 2.8 inches below normal. The mean wind speed was 11.1 mph, which was the lowest on record for April, and the prevailing wind direction was from the east-northeast. The highest wind gust was 46 mph from the northwest on the 12th. April bright sunshine was near average with 193.3 hours, or 50 percent of possible, which was one percent more than the long-term average for April.

BHO Warmest April Approximated 24-Hour Mean Temperature, deg F (1885-2023):

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) 49.0 in 1994

BHO Warmest April Average Maximum Temperature, deg F (1885-2023):

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

BHO Warmest April Average Minimum Temperature, deg F (1885-2023):

1) 41.8 in 2010
2) 41.5 in 1945
3) 41.3 in 2017
4) 40.9 in 2023
5) 40.5 in 1910
6) 40.4 in 1976
7) 40.1 in 2012

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

1) 11.1 in 2023
2) 12.0 in 2008
3) 12.3 in 2010
4) 12.4 in 2001
   12.4 in 2016
6) 12.5 in 2021

Mike Iacono
Chief Scientist
Blue Hill Observatory