June 2016 Summary – Seventh Sunniest on Record

Blue Hill Observatory
June 2016 Summary:

The month was notable for being generally warm and dry with much more sun than average. The 24-hour mean temperature for the month of 66.6 deg F was 2.5 degrees warmer than the 120-year average for June and more than a degree warmer than the 1981-2010 30-year average. The highest temperature for the month was 86F on the 26th and 30th, and the low temperature of 48F occurred on the 9th. There were no daily temperature records during the month. The 12-month average temperature from July 2015 through June 2016 was 52.0 deg F, which was the second warmest for this period on record.  Since the heating degree day season also extends from July through June, the total heating degree days for the 2015-2016 season of 5282 finished as the second lowest since 1885. The total cooling degree days during the month was 109, which was four more than average. The first ripe blueberries of the season were observed on the summit of Great Blue Hill on June 7th. This date ties for the second earliest on record and continues a slow trend to earlier dates each year. June precipitation totaled 1.62 inches, which was about two inches less than the long-term 120-year average and more than two a half inches less than the 30-year mean. Nearly half of the monthly total and the greatest amount in 24 hours, 0.76 inches, fell on the 5th. There were five days with thunderstorms in June, which is one more than average, and the annual total is now up to seven. The mean wind speed was 11.6 mph, with a prevailing direction from the south, and this direction was observed in an unusually high 24 percent of the hours during the month. The peak gust was 41 mph from the west-northwest on the 8th and from the west on the 12th. June sunshine was well above average with 69 percent of the possible bright sunshine being observed, which was 14 percent more than the long-term average, and the total duration of sunshine, 301.6 hours, ranked as the seventh highest on record for any June.

BHO Sunniest June, hours (1886-2016):

1) 336.5 in 1971 [76%] 2) 335.5 in 1908 [76%] 3) 327.4 in 1953 [74%] 4) 322.6 in 1949 [73%] 5) 313.7 in 1912 [71%] 6) 309.1 in 1965 [70%] 7) 301.6 in 2016 [69%]
8) 295.7 in 1978 [68%] 9) 295.3 in 1979 [68%] 10) 293.7 in 1901 [67%]

BHO Earliest Date of First Ripe Blueberry (1886-2016):

1) 5 June in 2012
2) 7 June in 2011
   7 June in 2016
4) 9 June in 1934
   9 June in 1944
6) 10 June in 1922
   10 June in 1991
   10 June in 1994

BHO Warmest July-June Temperature, deg F (1885-2016):

1) 52.5 in 2011-2012
2) 52.0 in 2015-2016
3) 51.0 in 1990-1991
4) 50.9 in 2001-2002
5) 50.6 in 1998-1999

BHO Fewest July-June Heating Degree Days, (1885-2016):

1) 4984 in 2011-2012
2) 5282 in 2015-2016
3) 5338 in 2001-2002
4) 5458 in 1990-1991
5) 5633 in 1998-1999

Mike Iacono
Chief Scientist
Blue Hill Observatory