How Does this Heat Wave Compare ?

 

Nationals Park, Washington, D.C.

Today will be the fourth consecutive 90° day during D.C.’s current heat wave, the first of the year.  There have been 15 days of 90° as of July 20, compared to 24 for the same period last year.  A “heat wave” is defined as a minimum of three consecutive 90° days. 

What makes the current heat wave significant is the potential on Sunday, July 24 for the first triple-digit heat since August 15, 2016.  This stretch of nearly six years without triple-digit heat is unusual because the Nation’s Capital has averaged at least one such day every three to four years in recent decades. 

Washingtonians are in the midst of the longest period of the last 30 years without 100° heat.  Prior to the current streak, there were three nearly four year stretches without 100° heat.  No triple-digit heat occurred between July 26, 2012 and July 25, 2016.  Also, none occurred between August 13, 2002 and August 3, 2006; as well as between July 28, 1993 and June 25, 1997. 

July is D.C.’s hottest month of the year with record highs of at least 100° on all but three days.  My colleagues and I on the WUSA9 Weather Team expect Sunday, July 24 to be the hottest day of the current heat wave with a high near 100°.  D.C.’s record high on July 24 is 101° set in 2010. 

While no triple-digit heat has occurred in Washington, D.C. in nearly six years, there have been several significant heat waves since then.  A 12-day heat wave occurred from July 11 – July 22, 2019.  It’s important to note that Dulles Airport reached 100° on July 21, 2019, so it was at least 100° more recently than in Washington, D.C. (as measured at National Airport).  A 20-day heat wave also occurred at National Airport from June 26 – July 15, 2020.