Area covered by heat advisory Wednesday (National Weather Service)

Link: Capital Weather Gang heat wave and hot weather guide

The actual air temperatures are likely to max out between 95-98 degrees Wednesday, but humidity levels will be high, with dew points in the upper 60s to near 70. That adds about 5-7 degrees to what it feels like.

A high in the mid-to-upper 90s would represent the hottest day this year (previous hottest 92 on June 10) and most likely the hottest since August 7, 2011 when it hit 97.


Record high temperatures Wednesday at the three local airports are:

Reagan National: 99 (1931)

Dulles: 97 (1964)

BWI: 100 (1931)

Dulles’ record is within reach, but the other two are a stretch.

As hot as it is Wednesday, it may turn even a little hotter Thursday with highs 96-100, with a greater likelihood of matching or besting records.

Thursday’s records are:

Reagan National: 98 (1988, tied in past years as well)

Dulles: 98 (1988)

BWI: 100 (1923)

Cause of the heat?

Last Friday, I provided an early heads-up about this heat wave, and described the cause accordingly:

...slowly but surely, a classic “Bermuda high” pattern will evolve. What happens is simple: as high pressure drifts from the East Coast over the Atlantic towards Bermuda, the clockwise circulation around it acts like a heat pump, channeling oppresively moist tropical air up the East Coast.

Cool so far

The heat follows a cooler than average June to date. The average temperatures has been 1.4 degrees below normal. We’ve had almost as many days with highs in the 70s (7) as in the 80s (9) and 90s (3). 10 of 19 days have been cooler than normal.

Turning cooler again next week?

CWG’s Greg Postel says the jet stream will take a dip across Northeast next week, likely bringing a return of cooler than average weather.