August 2017 Summary – Warmer, Drier and Sunnier than Average

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Blue Hill Observatory

August 2017 Summary:

August temperature was slightly warmer than normal with less rainfall and more sunshine than average. The 24-hour mean temperature for the month of 69.7 deg F was 1.6 degrees warmer than the 120-year average for August and 0.3 degrees warmer than the 1981-2010 30-year average. The high temperature of 89F occurred on the 19th. The coldest temperature during August was 55F on the 26th, 27th, and 31st. A total of 1.60 inches of precipitation was measured during August, which was about two and a half inches less than the long-term 120-year average and the 30-year mean. The greatest amount in 24 hours was 1.09 inches (about two-thirds of the monthly total) during evening thunderstorms on the 2nd. This was the only thunderstorm day during August, which brings the annual total up to 13. Through August, there has been at least one thunderstorm day observed in each month so far this year, which has only happened once before (in 1996) during the entire Blue Hill climate record. The mean wind speed for August was 10.0 mph, which tied for the third lowest on record for the month, and the prevailing direction was from the south. The peak gust was 33 mph from the south on the 18th, and this was the second lowest August peak gust on record in the last fifty years behind only 28 mph in 1996. August bright sunshine was above average with 268.0 hours or 65 percent of possible, which was seven percent more the long-term mean. The solar eclipse of August 21, 2017, during which the moon covered about 63% of the solar disk at mid-afternoon during the peak of the eclipse at Blue Hill, temporarily dropped the temperature as much as 5 deg F and measurably reduced the intensity of sunshine as recorded at Blue Hill.

BHO August Lowest Mean Wind Speed, mph (1885-2017):

1) 9.5 in 1996
   9.5 in 2008
3) 10.0 in 1899
   10.0 in 2009
   10.0 in 2012
   10.0 in 2015
   10.0 in 2017

Summer (Jun-Aug) 2017 Summary:

Summer 2017 featured generally warmer than average weather with close to normal rainfall. The 24-hour mean temperature for Summer of 69.0 deg F was 1.7 degrees warmer than the 120-year average and 0.5 degrees warmer than the 1981-2010 30-year normal. There were five ninety-degree days during Summer, which was about average, with only one heat wave on July 19th-21st. The season began wetter than average and became increasingly dry through August. The precipitation total of 11.02 inches was under a half inch less than the long-term mean and more than an inch drier than the 30-year mean. The Summer mean wind speed of 10.7 mph tied for the fifth lowest on record. Bright sunshine during the Summer was 66 percent of possible, which was four percent more than average.

Photo Credit- Lee Toma

Mike Iacono
Chief Scientist
Blue Hill Observatory