August 2019 Summary – Warmer, Drier and Sunnier Than Average

Blue Hill Observatory

August 2019 Summary:

August was generally warm and sunny with less rainfall than average. The 24-hour adjusted mean temperature for the month of 70.5 deg F was 2.4 degrees warmer than the 120-year average for August and 1.1 degrees warmer than the 1981-2010 30-year average. The average maximum temperature of 80.4 deg F was 1.2 degrees above normal, and the average minimum temperature of 62.1 deg F was 0.3 degrees above normal. The warmest temperature for the month was 92F on the 19th, the seventh ninety-degree day of the year, and the lowest temperature was 51F on the 26th. Precipitation totaled 1.83 inches, which was more than two inches less than the long-term 120-year average and the 30-year mean. Most of the monthly rainfall fell on just four days, and the greatest precipitation in 24 hours was 0.81 inches on the 28th-29th. There were three thunderstorm days during August, one less than average, including several separate thunderstorms on the 21st. The mean wind speed was 9.8 mph, which was the third lowest on record for August and tied for the fourth lowest for any month. The prevailing wind direction for the month was from the west. A peak gust of 33 mph from the southwest occurred during the thunderstorms on the 21st. August brought abundant sunshine with 273.4 hours, or 66 percent of the possible bright sunshine, which was eight percent more than the long-term average.

BHO Lowest August Mean Wind Speed, mph (1885-2019):

1) 9.5 in 1996
   9.5 in 2008
3) 9.8 in 2019
4) 10.0 in 1899
   10.0 in 2009
   10.0 in 2012
   10.0 in 2015
   10.0 in 2017

Summer (June-August) 2019 Summary:

Summer 2019 was generally warm and very sunny with near average rainfall. The 24-hour adjusted mean temperature for summer of 70.3 deg F was 3.0 degrees warmer than the 120-year average for June-August and 1.8 degrees warmer than the 1981-2010 30-year summer average. This was the seventh warmest summer on record. There were seven ninety-degree days, one more than average, and no heat waves, though the last four days of July had high temperatures of 89F or more.  Summer precipitation totaled 11.37 inches, what was very close to the 120-year long-term mean and about an inch less than the 30-year normal. The greatest rainfall in 24 hours was 2.08 inches on July 22nd-23rd, which resulted in the temperature dropping from the low 90’s on the 21st to highs in the middle 60’s on the 23rd. There were nine thunderstorm days during June-August, which was four less than average. The average wind speed recorded during summer was just 10.0 mph, which was the lowest ever measured for summer and for any three-month season. Sunshine was above average during summer, and 63 percent of the possible bright sunshine was observed, which was six percent more than the long-term mean.

BHO Warmest Summer (Jun-Aug) 24-hour Adjusted Mean Temperature, deg F (1885-2019):

1) 71.6 in 2016
2) 71.3 in 2010
3) 70.9 in 2018
4) 70.8 in 1949
5) 70.6 in 1999
6) 70.4 in 1952
7) 70.3 in 2019
8) 70.2 in 2005

BHO Lowest Summer (Jun-Aug) Mean Wind Speed, mph (1885-2019):

1) 10.0 in 2019
2) 10.2 in 2012
3) 10.3 in 2008
   10.3 in 2009
5) 10.4 in 2015
6) 10.5 in 2018

Mike Iacono
Chief Scientist
Blue Hill Observatory