The 2017 Summer

Great Falls, Maryland 

A week of temperatures more characteristic of early June than early August is on tap for Washingtonians, despite starting the month with four consecutive days at 90°/+.  No 90° heat is on the seven-day forecast in the Nation’s Capital.  That’s a far cry from the above average temperatures that occurred for much of June and July.

A cooler than average first half of August would also be considerably different than August 2016.  Last August was the second hottest on record in Washington, D.C. with 23 days at 90°/+ including three consecutive days at 100°/+.  That was the first time Washingtonians experienced two or more consecutive days of triple-digit heat during the month of August since 1997.  

The hottest temperature so far this summer occurred on July 20 (98°).  Last month was the fifth wettest July on record, but was only the twelfth warmest.  Aside from the lack of triple-digit heat this summer, another key difference compared to last year can be found among the frequency of 90° days in Washington, D.C.

Although last year saw an unusually high number of 90° days (58), the first didn’t occur until June 11, 2016.  By comparison, the first day of 90° heat this year occurred on April 29 (91° at National Airport).  According to the National Weather Service, Washington, D.C. averages 36 days at 90°/+ in a given year.  2017 currently stands at 34 such days.  Average high temperatures in Washington, D.C. fall from 88° on August 1 to 84° on August 31.

While four of the last five Augusts have been drier than average in the Nation’s Capital, today’s rainfall could go a long way toward making this month wetter than average.  Triple-digit heat is relatively rare in the Mid-Atlantic Region.  While it’s been 100° as late in the year as September 8 (1939) in Washington, D.C., triple-digit heat gets less and less likely as August wears on.