Summer Loosens Its Grip

Washingtonians have had a Hot Summer of 2016  (Source: WUSA9)

The summer-like weather pattern that has dominated headlines much of this past week is coming to an end.  A multitude of record highs were set from North Carolina to Massachusetts, while record heat also occurred at Dulles Airport and in Baltimore.  In fact, the weather during the first ten days of September was hardly discernable from the torrid weather that Washingtonians experienced in July and August.  

Longtime residents have grown accustomed to a few hot September days.  There has been 90 degree heat in September in eight of the last ten years, including every September since 2010.  National Weather Service data indicates the temperature of 98 degrees on September 8 was the hottest September temperature in the Nation’s Capital since September 24, 2010 (99 degrees).  Triple-digit heat is rare in September, having occurred only once since National Airport opened in 1941 (101 degrees on September 2, 1980).

A heat wave is defined as a minimum of three consecutive days with high temperatures of 90 degrees or hotter.  The current heat wave began on Tuesday, September 6 with a high temperature of 94 degrees at National Airport.  Although Dulles and BWI Airports have set record highs this week, National Airport fell short.  Something rare did occur this week at National Airport, however.  With Saturday’s high temperature of 95 degrees, Washington, D.C. has had three consecutive September days with temperatures of 95 degrees or higher. 

That’s only happened twice previously – in 1881 and more recently in 1985, when September featured four consecutive days of temperatures at or above 95 degrees.  Another impressive illustration of how hot 2016 has been is the total of 56 days of temperatures at or above 90 degrees in the Nation’s Capital.  That’s the highest such total since the record of 67 days which occurred in 2010 (and in 1980).  Washington, D.C. averages only 36 days at/above 90 degrees, so 2016 is significantly above average.  Among the 56 days at/above 90 degrees, 22 of those days have been at least 95 degrees and four reached triple-digits.

Septembers aren’t always hot in the Nation’s Capital.  For example, in 1996, 1999 and 2003 Washingtonians experienced above average rainfall and cooler than average monthly temperatures.  What each of those Septembers had in common was an appreciable amount of rainfall from a decaying tropical system.  However, there aren’t currently any active tropical storms or hurricanes lurking in the Atlantic Ocean.

Fortunately for those eager for cooler and less humid weather, today will be a stellar day with highs in the 80s.  By the end of the week, Washingtonians could see the coolest weather in several months with high temperatures only near 80 degrees possible.  My colleagues and I on the WUSA9 weather team will keep you apprised of the latest weather developments both on-air and on the free WUSA9 app for your mobile devices.