A Preview of Summer

Beautiful Spring Weather in Germantown, MD  (May 2015)

If you think this month has been warmer than average in the Mid-Atlantic, then you would be correct.  In fact, temperatures have been warmer than average on 13 of the first 16 days of the month in the Nation’s Capital.  That includes the first 90 degree day of 2015 in Washington, D.C., that came on May 12.  Through May 12, the month was an astounding 9 degrees warmer than average.

What’s helped make this May so warm was the stretch of 10 consecutive days with highs in the 80s.  That’s very unusual in May in the Nation’s Capital because the average high temperature doesn’t reach 80 degrees in Washington, D.C. until May 31.  Although no daily record highs have been set this month, the monthly average temperature (combining the daily high and low temperatures) at National Airport through yesterday was 71.2 degrees.  That would make this May the 5^th warmest on record.  The warmest May on record in the Nation’s Capital came in 1991 (when the average May temperature was 73 degrees).

Although today’s average high temperature is 76 degrees downtown, today’s actual high was 87 degrees at National Airport.  That’s the average high on June 24 in the Nation’s Capital.  Temperatures will return to more seasonal levels on Wednesday in the mid to upper 70s.  That will help keep this month’s average temperature among the warmest May’s on record.  According to NOAA’s Climate Prediction Center, the national temperature outlook for the next one to two weeks calls for continued warmer than average temperatures in the Mid-Atlantic Region. 

Until yesterday’s thunderstorms brought appreciable rainfall to the Mid-Atlantic Region, the DC Metro Region had been in the midst of an exceptionally dry month.  In fact, the Drought Monitor Index indicates that “abnormally dry” conditions exist across much of Eastern Pennsylvania and North Central Maryland.  Although May averages 3.99” of rain, National Airport has observed only 0.82” of rain so far this month (with the bulk of that occurring yesterday). 
  

Scattered thunderstorms are possible through Tuesday when a cold front will pass through the Mid-Atlantic Region ushering in more seasonal temperatures and less humid air for the second half of the work week.  Although scattered thunderstorms can bring heavy rain where they occur, no widespread rainfall is expected. 

According to the National Weather Service, May has to finish with an average temperature of at least 70.5 degrees to be the 5^th warmest on record in the Nation’s Capital.  My colleagues and I on the WUSA9 Weather Team will keep you apprised on the latest weather forecasts.