May 2015 Summary – Warmest on ...

May 2015 Summary – Warmest on Record

Blue Hill Observatory
May 2015 Summary:

The month was notable for being very warm, sunny and generally dry. The 24-hour mean temperature for the month of 61.5 deg F was 6.2 degrees warmer than the 120-year average for May, making this the warmest May on record and just surpassing the previous record of 61.4 deg F in May 1991.  The maximum temperature for the month was 88F on the 10th, and the coolest temperature was 35F on the 2nd.  The average maximum temperature for the month was 74.6 deg F, which is the highest on record, surpassing 74.4 deg F in May 1944. Twenty-three days during May were warmer than average. The month was very dry with a precipitation total of 1.45 inches, which was more than two inches less than the 120-year average and the 1981-2010 mean. Only 0.63 inches was observed through the 30th, and 0.82 inches fell on the last day of the month. The warmth and dryness contributed to elevated brush fire risk throughout the month.   There was one day with a thunderstorm on the 31st. The mean wind speed for the month was 12.6 mph, and the prevailing direction was from the south-southwest. The peak gust for the month was 40 mph from the northeast during the rain on the 31st. May sunshine totaled 282.5 hours, or 65 percent of the possible bright sunshine, which was thirteen percent more than the long-term average. This was the ninth sunniest May on record and the sunniest since 2010.

BHO Warmest Mays, deg F (1885-2015)

1) 61.5 in 2015
2) 61.4 in 1991
3) 61.0 in 1944
4) 60.9 in 2010
5) 59.4 in 1911
59.4 in 1959

BHO Warmest May Average Maximum Temperature, deg F (1885-2015)

1) 74.6 in 2015
2) 74.4 in 1944
3) 73.9 in 1991
4) 72.3 in 2010
5) 71.9 in 1955

BHO Fewest Number of Days Measurable Precipitation, May, (1885-2015)

1) 3 in 1964
2) 4 in 1932
4 in 2015
4) 6 in 1939
6 in 1977

BHO Sunniest Mays, hours (1886-2015)

1) 318.9 in 1964
2) 304.5 in 1977
3) 295.8 in 1955
4) 288.4 in 1991
5) 287.5 in 2010
6) 286.5 in 1922
7) 286.2 in 1944
8) 283.6 in 1965
9) 282.5 in 2015
10) 278.4 in 1936