Putting this week's Heat Wave into Perspective

Keeping cool in a comfortable spot in Washington, D.C.  (June 2015)

Although this past week was the hottest of the year and featured the longest heat wave in nearly two years, no new record highs were set. On Tuesday, June 16 the temperature reached 96 degrees, which was the hottest temperature in the Nation’s Capital since August 31, 2014.

This week’s heat wave began on June 11 and continued through Tuesday, June 16. Washingtonians have to go back to 2013 to find the last stretch of six or more 90 degree days (July 15 –21).  That’s why residents of the Nation’s Capital are correct to say that the weather has been unusually hot of late. However, it hasn’t been unprecedented.  Area residents endured triple digit heat in three consecutive Junes starting in 2010.  The hottest June temperature on record in Washington, D.C. occurred in that time when it was 104 degrees on June 29, 2012.

This spring was relatively short in the Mid-Atlantic Region with below average temperatures spanning most of March, while May was the warmest on record downtown. Data from the National Weather Service indicates this month has been more than 3 degrees warmer than average in the Nation’s Capital through June 17.  However, this month hasn’t approached the degree of heat that the warmest June on record (2010) featured.

The weather pattern became very summer-like last month because the “Bermuda High” set up earlier in the season than it normally does. The Bermuda High is a semi-permanent area of high pressure that typically sits off the East Coast of the United States during the summer months. This allows it to pump warm and humid air from the Deep South into the Mid-Atlantic Region. It’s known as the “Bermuda High” since that’s where it’s typically centered.

When the U.S. Climate Prediction Center issued the temperature outlook for June, it called for above average temperatures across the Mid-Atlantic Region. In fact, the 90s are poised to return early next week in the Nation’s Capital.  Average high temperatures during the second half of June only range from the mid to upper 80s.

It’s important to note that a warmer than average June doesn’t necessarily mean the entire summer will be warmer than average.  For instance, last June was warmer than average in the Nation’s Capital, but the average temperatures for July and August 2014 were both within a half degree of “average.”  My colleagues and I on the WUSA9 Weather Team will keep you posted on the latest weather forecasts as the summer progresses.