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Today: Mostly sunny, hot & humid. Mid-to-upper 90s. | Tonight: Mostly clear & muggy. 70s. | Tomorrow: Mostly to partly sunny & scorching. Chance of late-day storms. Upper 90s to near 100. | A Look Ahead | Get Express Forecast by E-mail
Sinking air is the signature of the hottest days here in the D.C. area - when air sinks it warms - and we’ve got plenty of it today and tomorrow as an upper-level area of high pressure pushes the air down from above, while breezes near the surface blow downhill from the west/southwest. The result is two days of potentially record-tying or record-breaking heat with afternoon heat indices near or over 100, followed by slightly cooler air and storm chances late Thursday through Sunday as a cold front stalls nearby.
Today (Wednesday): Morning temperatures climb quickly into and through the 80s and we’ll probably top 90 by lunchtime. With mostly sunny skies and a light but warming breeze from the west/southwest, afternoon highs should soar into the mid-to-upper 90s. The records in jeopardy are 98 at National (1999), 97 at Dulles (2007) and 97 at BWI (1999). The high humidity likely pushes the afternoon heat index past 100. Confidence: High
Tonight: Mostly clear and oh-so-muggy with evening temps slowly dropping into the 80s and overnight lows in the balmy 70s. The record high minimum temperature may be challenged at both National (77 in 2008) and Dulles (70 in 1990). Confidence: High
Keep reading for the forecast through the weekend...
Tomorrow (Thursday): Mostly to partly sunny and similar to today except maybe a couple degrees warmer every step of the way, with afternoon highs in the upper 90s to near 100 and possibly a few late afternoon t’storms (30% chance) with the approach of a cold front. The heat index may very well reach 105-110 at some point in the afternoon. The record high at National is a tough one to equal or beat - 102 in 1874 - but not completely out of the question. Dulles is more doable (96 in 1999) as is BWI (98 in 1933). Confidence: Medium-High
Tomorrow night: Partly cloudy with with the potential (40% chance) for some evening storms. Lows are mainly in the 70s, which means another shot at record high minimums - 75 at National (2005) and 72 at Dulles (2005). Confidence: Medium
High temperatures on Friday should come down a bit. But low-to-mid 90s is still steamy with partly sunny skies, moderate to high humidity, and a 50% chance of showers and storms thanks to a stalled cold front in the vicinity. Showers or storms may linger Friday night as lows remain mild, in the upper 60s to mid-70s . Confidence: Medium
Rather than pushing through and drying the air out at least a bit, that cold front is poised to hang around through the weekend. So we’re likely to stay on the humid side with partly sunny skies, highs in the 80s to near 90, and a decent chance of isolated to scattered storms each day. Confidence: Medium