July 2019 Summary – Third Warmest on Record

Blue Hill Observatory

July 2019 Summary:

July was generally very warm and wetter than average. The 24-hour adjusted mean temperature for the month of 74.5 deg F was 4.8 degrees warmer than the 120-year average for July and 3.7 degrees warmer than the 1981-2010 30-year average. The month was the third warmest July on record, and it was the third warmest for any month of the year. The average maximum temperature of 84.6 deg F was 3.8 degrees above normal and the sixth highest on record, while the average minimum temperature of 65.6 deg F was 2.7 degrees above normal and tied for the third highest on record. The warmest temperature for the month was 93F on the 20th and 30th, and the lowest temperature was 58F on the 1st and 23rd. The highs of 93F were the warmest temperatures of the year so far. Although there were no heat waves during July several periods came very close including highs of 89F, 93F and 92F on the 19th-21st, and highs of 89F, 89F, 93F, and 90F on the 28th-31st. The low temperature of 58F tied for the second highest monthly minimum temperature on record for July. There were two daily record high minimum temperatures during the month including 75F on the 20th, which surpassed the previous record of 73F set in 1977 and 2015, and 76F on the 21st, which surpassed the previous record for that date of 75F set in 1991. Precipitation totaled 5.46 inches, which was nearly two inches more than the long-term 120-year average and about an inch and a half more than the 30-year mean. The greatest precipitation in 24 hours was 2.08 inches on the 22nd-23rd. There were three thunderstorm days during July, two fewer than average, which brings the annual total up to eleven. The mean wind speed was 9.6 mph, which was the lowest on record for July and the third lowest for any month, and the prevailing direction was from the west. A peak gust of 44 mph from the west occurred during thunderstorms on the 17th. July brought abundant sunshine with 305.0 hours, or 69 percent of the possible bright sunshine, which was eleven percent more than the long-term average.

BHO Warmest July 24-Hour Mean Temperature, deg F (1885-2019):

1) 75.1 in 2010
2) 74.9 in 1952
3) 74.5 in 2019
4) 74.1 in 1994
   74.1  in 2013
6) 74.0 in 2011
   74.0 in 2016

BHO Warmest Monthly 24-Hour Mean Temperature, deg F (1885-2019):

1) 75.1 in July, 2010
2) 74.9 in July, 1952
3) 74.5 in July, 2019
4) 74.1 in July, 1994
   74.1  in July, 2013
   74.1  in August, 2016
7) 74.0 in July, 2011
   74.0 in July, 2016

BHO Warmest July Average Maximum Temperature, deg F (1885-2019):

1) 87.2 in 1952
2) 86.5 in 2010
3) 85.5 in 1949
4) 84.9 in 1994
5) 84.7 in 2016
6) 84.6 in 2019
7) 84.5 in 1911

BHO Warmest July Average Minimum Temperature, deg F (1885-2019):

1) 66.9 in 2013
2) 65.9 in 2010
3) 65.6 in 1994
   65.6 in 2019
5) 65.3 in 2006
6) 65.1 in 2008
7) 64.9 in 1999

BHO Highest July Monthly Minimum Temperature, deg F (1885-2019):

1) 59 in 2008
2) 58 in 2006
   58 in 2011
   58 in 2012
   58 in 2019
6) 57 in 1887
   57 in 2003
   57 in 2004
   57 in 2013

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

1) 9.6 in 2019
2) 9.8 in 2012
3) 10.0 in 2017
4) 10.1 in 1906
   10.1 in 2013
6) 10.2 in 2015

Mike Iacono
Chief Scientist
Blue Hill Observatory