An Early Taste of Summer

Residents of the D.C. Metro Area got a taste of summer-like weather this week with the first heat wave of 2018.  High temperatures reached at least 90° on three consecutive days in the Nation’s Capital through May 4, the official definition of a “heat wave.”  Temperatures have been warmer than average the first five days of May.

Washington, D.C. set a record high of 91° on May 2, which was also D.C.’s first 90° day since September 27, 2017.  According to National Weather Service data, D.C.’s May 2 – May 4 was D.C.’s earliest heat wave since April 16 – 18, 2002.  It was also D.C.’s first heat wave to occur in the first week of May and the first May heat wave, overall, since May 29 – 31, 2013.  Baltimore, Maryland set record highs of 92° and 91°, respectively, on May 3 and May 4 (at BWI Airport).  Meanwhile, at Dulles Airport in Sterling, Virginia, record-tying highs of 88° and 90° occurred on May 2 and May 4. 

Washingtonians have averaged one to two days in the 90s during the month of May since 1993.  Some may remember that May 2015 was D.C.’s warmest May on record with seven 90° days, but no more than two occurred consecutively.  By comparison, May 2016 finished more than two degrees cooler than average with no 90° heat. 

Having 90° heat in May isn’t a reliable indicator of what the upcoming summer will be like.  For example, May 2016 finished with a temperature 2.1° below average.  However, the summer of 2016 included D.C.’s sixth hottest July and second hottest August according to NOAA.  Overall, 2016 was the third warmest meteorological summer in the Nation’s Capital.  Conversely, 2015 had D.C.’s warmest May on record, but that didn’t even rank among D.C.’s 10 warmest summers.

This helps illustrate that while record heat in May can foreshadow a hot summer, it can also be an anomaly.  NOAA expects a warmer than average May in the DC Metro Area this year. 

 

NOAA's temperature outlook for May 2018