April 2021 Summary – Warmer and Sunnier Than Average

Blue Hill Observatory April 2021 Summary:

April was warmer and much sunnier than average. The 24-hour adjusted mean temperature for the month of 47.0 deg F was 2.1 degrees warmer than the 1891-2020 130-year average for April, and it was 0.7 degrees warmer than the 1981-2010 30-year average. The average maximum temperature of 57.2 deg F was 1.5 degrees warmer than the 30-year mean, and the average minimum temperature of 37.8 deg F was just 0.1 degrees warmer than the 30-year mean. The highest temperature observed all month was 75F on the 10th, and the lowest temperature was 23F on the 3rd. April total precipitation was 4.89 inches, which was about three-quarters of an inch more than the long-term 130-year average and a third of an inch more than the 1981-2010 30-year mean. More than half of this precipitation, 2.59 inches, fell during a cold rain storm on the 15th-17th, which included 2.22 inches of liquid precipitation and more than three inches of snowfall on the 16th. The greatest precipitation in 24 hours was 2.45 inches on the 15th-16th. Total snowfall for the month was 3.6 inches, which was the total on the 16th, and this amount was also the greatest snowfall in 24 hours. A thunderstorm was observed on the 21st during the passage of a strong cold front. The mean wind speed for the month was 12.5 mph, which was the fifth lowest on record for April, and the prevailing wind direction was from the west-northwest. The monthly peak wind gust was 58 mph from the west-northwest on the 30th. April sunshine was above average at 207.4 hours, which was 54 percent of the possible bright sunshine and 5 percent more than the long-term average.

BHO Lowest April Mean Wind Speed, mph (1885-2021):

1) 12.0 in 2008
2) 12.3 in 2010
3) 12.4 in 2001
   12.4 in 2016
5) 12.5 in 2021
6) 12.6 in 2018

Mike Iacono
Chief Scientist
Blue Hill Observatory