What is August like in the Nation's Capital?

A Great Place to Cool Off!  (Great Falls, MD) 

As some may know, August is the third and final month of “meteorological summer.”  Although average high temperatures fall during the month, August is still quite warm across the Mid-Atlantic Region.  While July is the hottest month on average in the Nation’s Capital, every so often the month of August is hotter and that happened as recently as 2009.

The average high at National Airport on August 1 is 88 degrees, but that falls to 84 degrees by August 31.  Official weather observations for Washington, D.C have been measured at Reagan National Airport since it opened in 1941.  Washington, D.C.’s hottest August temperature on record is 106 degrees on August 6, 1918 and on July 20, 1930.  The last time there was triple digit heat during the month of August in the Nation’s Capital was in 2011.  August’s coolest temperature at National Airport is 49 degrees.  That’s happened three times – as recently as August 29, 1986. 

According to the National Weather Service, August averages 3.44” of rain.  The wettest August on record in Washington, D.C. was in 1928 when 14.41” fell.  On the opposite end of the spectrum, the driest August on record was in 1962 when only 0.55” of rain fell.  The tropics typically get more active during the month of August and the Mid-Atlantic Region sometimes sees enhanced rainfall as a result.  Many Washingtonians will recall the heavy rain, high winds and coastal flooding caused by Hurricane Irene in late August 2011.

Today will be the 11^th consecutive day with temperatures of at least 90 degrees in the Nation’s Capital – the longest such stretch since 2012.  Fortunately, this summer has also had above average rainfall in addition to above average temperatures, making the heat less taxing on area reservoirs and gardens.  Since June 1, Washington, D.C. has a rainfall surplus of 9.33”.  As this week progresses, temperatures will cool to more seasonal levels in the 80s as the prospect of showers and thunderstorms return.