Just How Hot Was this Week in the Nation's Capital?

Keeping Cool in Great Falls, MD

Washingtonians got their first real taste of summer this week with temperatures and relative humidity more characteristic of Independence Day.  Although downtown Washington, D.C. didn’t meet the official criteria of a heat wave (at least 3 consecutive days at or above 90°), Dulles and BWI Airports both did.  

In fact, Dulles and BWI Airports experienced some record heat this week while National Airport fell short.  This week’s summer-like temperatures represented a major shift in the weather pattern compared to the cooler than average first half of the month.  It was also the warmest May weather in the Nation’s Capital since 2015.  It’s also important to point out that May 2015 was the warmest May on record in Washington, D.C.

The hottest temperature this week at National Airport was 93°.  Although not a record high, yesterday’s temperature was DC’s hottest May temperature since May 31, 2011 (98°).  It was also the third 90° day in the Nation’s Capital of the year.  The third 90° day didn’t occur last year until June 19.  However, most DC residents will remember last summer for the very hot weather that occurred in July, August and September instead of the cooler than average May 2016. 

Although average high temperatures are in the 70s for most of May in Washington, D.C., warmer temperatures are fairly common.  Since 1993, the Nation’s Capital has averaged approximately four May days with temperatures of at least 85° and a little over one day with 90° temperatures.  Over the last two and a half decades, Washingtonians have seen May temperatures of 95° or greater roughly every four years.  According to the National Weather Service, Washington, D.C.’s earliest 100° temperature was on June 5, 1925.

While the first two weeks of this month were more than 2° below average in Washington, D.C., this week’s heat helped push May’s average temperature to being 0.3° above average through May 19.  However, the weather pattern has shifted again and NOAA expects below average temperatures into early June.  While a warmer than average day or two is entirely possible between now and then, Washingtonians could end up with their first cooler than average month since last May.