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Blue Hill Observatory April 2020 Summary:
April was unusually cold, wet and cloudy with near average snowfall. The 24-hour adjusted mean temperature for the month of 42.9 deg F was 1.8 degrees colder than the 120-year average for April and 3.4 degrees colder than the 1981-2010 30-year average. Cold daily high temperatures were persistent throughout the month. The average maximum temperature of 50.6 deg F was more than 5 degrees colder than the 30-year mean, and this mean was the seventh lowest on record and the coldest since 1940. The average minimum temperature of 35.8 deg F was 1.9 degrees colder than the 30-year mean. The highest temperature observed all month was only 63F on the 7th, and this reading was the coldest April monthly maximum temperature on record. The lowest temperature was 28F on the 1st. Twenty-two of the thirty days during the month were colder than average, including every day from the 15th to the 30th. Precipitation totaled 7.71 inches, which was more than three and a half inches more than the long-term 120-year average and about three inches more than the 30-year mean. This amount was the seventh highest on record for April. The greatest precipitation in 24 hours was 2.23 inches on the 3rd-4th. Snowfall in April totaled 4.3 inches, which was 2.4 inches more than the 30-year mean and the most snowfall in any month so far during 2020. The greatest snowfall in 24 hours was 4.3 inches on the 18th, which surpassed the previous record for the date of 3.7 inches in 1965 and was the fourth largest snowfall so late in the season on record. The combined snowfall for January through April was only 11.9 inches, which was the second lowest on record behind only 7.5 inches observed in Jan-Apr 1937. The mean wind speed for the month was 14.3 mph, and the prevailing wind direction was from the west. This mean wind speed was the highest for any month since March 2018, and it was the highest in April since 2004. The monthly peak gust was 79 mph from the south during a strong rain storm on the 13th, and this gust was a new record for the date surpassing 59 mph from the south-southwest observed in 1995. This gust was also the third highest recorded in April since 1956. April was much cloudier than average with 139.3 hours of bright sunshine, or 36 percent of possible, which was thirteen percent less than the long-term average, and April was the eighth cloudiest on record.
BHO Lowest April Average Maximum Temperature, deg F (1885-2020):
1) 47.7 in 1917
2) 47.9 in 1901
3) 48.3 in 1907
4) 48.7 in 1916
5) 48.8 in 1898
6) 49.2 in 1888
7) 49.6 in 1939
49.6 in 1940
9) 50.4 in 1920
10) 50.6 in 2020
BHO Lowest April Monthly Maximum Temperature, deg F (1885-2020):
1) 63 in 2020
2) 66 in 1924
3) 67 in 1893
67 in 1916
67 in 1939
67 in 1946
67 in 1966
8) 68 in 1904
68 in 1975
BHO Highest April Precipitation, inches (1885-2020):
1) 10.37 in 1987
2) 9.38 in 2004
3) 8.71 in 1929
4) 8.68 in 2007
5) 8.53 in 1904
6) 8.14 in 2019
7) 7.71 in 2020
8) 7.57 in 1935
7.57 in 1983
10) 7.31 in 1901
BHO Highest Late Season Snowfall, inches (1885-2020):
1) 7.8 on 9-10 May 1977
2) 11.0 on 28-29 April 1987
3) 8.0 on 28 April 1916
4) 4.3 on 18 April 2020
5) 3.7 on 18 April 1965
BHO Highest April Wind Gust, mph (1956-2020):
1) 83 on 3 April 1977
2) 80 on 4 April 1963
3) 79 on 13 April 2020
4) 76 on 5 April 1963
76 on 20 April 1963
76 on 3 April 1970
7) 75 on 1 April 1962
BHO Lowest April Sunshine, hours (1885-2020):
1) 82.6 in 1901 [21%]
2) 121.1 in 1987 [31%]
3) 121.7 in 1988 [31%]
4) 131.6 in 1983 [34%]
5) 132.2 in 1921 [34%]
6) 137.3 in 2019 [35%]
7) 138.1 in 1939 [36%]
8) 139.3 in 2020 [36%]
9) 140.7 in 1955 [36%]
10) 141.1 in 2000 [36%]
Mike Iacono
Chief Scientist
Blue Hill Observatory
