May 2020 Summary – Drier and Sunnier Than Average

| June 13, 2020 | Reply

Blue Hill Observatory May 2020 Summary:

May was unusually dry and sunny with variable temperatures. The 24-hour adjusted mean temperature for the month of 56.1 deg F was 0.8 degrees warmer than the 120-year average for May, but it was 0.1 degrees colder than the 1981-2010 30-year average. The average maximum temperature of 67.2 deg F was about 1 degree warmer than the 30-year mean. The average minimum temperature of 45.8 deg F was 2 degrees colder than the 30-year mean. The highest temperature observed all month was 84F on the 27th, and the lowest temperature was 31F on the 10th. This was the latest freeze since 32F was recorded on May 10th, 1977. However, it was followed by another freezing temperature of 32F on the 13th, which surpassed the previous daily record minimum temperature of 35F set in 1914 and 2005. This reading was also the second latest freeze ever recorded at the Observatory behind only 30F observed on May 16th, 1936. May precipitation totaled 2.75 inches, which was about an inch less than the long-term 120-year average and nearly an inch and a half less than the 30-year mean. The greatest precipitation in 24 hours was 0.94 inches on the 1st. Snowfall in May totaled a trace, which was recorded on the morning of the 9th. The final 2019-2020 seasonal snowfall was 31.9 inches, which was the lowest for any season since 24.2 inches was measured in 2011-2012. There was one thunderstorm during May that occurred late in the day on the 15th. The mean wind speed for the month was 12.7 mph, and the prevailing wind direction was from the west. The monthly peak gust was 52 mph from the west on a cool, breezy day following some rain and a trace of snow. May was much sunnier than average with 270.8 hours of bright sunshine, or 62 percent of possible, which was ten percent more than the long-term average.

Spring (Mar-May) 2020 Summary:

Spring 2020 was generally warmer, wetter and sunnier than average. The 24-hour adjusted mean temperature for the Spring season of 46.5 deg F was 1.7 degrees warmer than the 120-year average, and it was 0.4 degrees warmer than the 1981-2010 30-year average. Cool temperatures during the second half of April extended into mid-May, with the second latest freeze on record being observed on May 13th. Precipitation during Spring totaled 15.13 inches, with about half of this amount occurring in April, and this total was nearly three inches more than the 120-year average and about an inch more than the 30-year normal. Spring snowfall of 7.1 inches was about eight inches less than average. Spring was slightly sunnier than average with 51 percent of the possible bright sunshine, which was one percent more than the long-term Spring average of 50 percent.

BHO Latest Freezing Temperature, deg F (1885-2020):

1) 30F on 16 May 1936
2) 32F on 13 May 2020
3) 29F on 12 May 1907
   30F on 12 May 1963
5) 28F on 11 May 1900
   31F on 11 May 1907
   31F on 11 May 1913
   30F on 11 May 1923
9) 29F on 10 May 1900
   31F on 10 May 1902
   31F on 10 May 1947
   32F on 10 May 1966
   32F on 10 May 1977
   31F on 10 May 2020

Mike Iacono
Chief Scientist
Blue Hill Observatory


Category: Weather Summary Archives

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