The Washington Post

PM Update: Extreme heat to drop a notch Wednesday

Although temperatures today warmed a few degrees compared to yesterday, it actually felt cooler due to modestly lower humidity levels. Today’s peak heat index values ranged from 100-103 compared to 103-105 yesterday. Tomorrow, the downward trend in humidity continues and temperatures step down a few degrees too. The big drop in humidity arrives tomorrow night, but we may have to get through some showers/storms first.

Temperatures: Latest D.C. area temperature map powered by iMapWeather (base map by Google). Click and hold on map to pan. Double-click to zoom. Refresh page to update. See larger map on our Weather Wall.

Through Tonight: Skies are mostly clear but you won’t notice much relief from the mugginess yet. With dew points area-wide in the upper 60s, that serves as the bottom for minimum temps in the cooler suburbs, whereas downtown D.C. can only manage the mid-70s.

Tomorrow (Wednesday): Full relief from the heat still isn’t here. The morning is steamy, and afternoon temps reach the low 90s with heat indices in the mid-to-upper 90s. Between mid-afternoon and early evening, there’s a 30-40% chance of showers and thunderstorms as a cold front moves through. After that front moves through, you should notice drier, more comfortable air steadily flowing in.

See Matt Rogers’ forecast through early next week. And if you haven’t already, join us on Facebook and follow us on Twitter

Pollen update: Grass pollen is LOW (NAB range) at 4.15 gr/cubic meter which is more moderate for our local area count. Tree pollen is LOW at 1.6 gr/cubic meter, weed pollen is LOW at 3.83 gr/cubic meter and mold spores are in the HIGH range at 22751.78 spores/cubic meter.

Jim Cantore: Today marks meteorologist Jim Cantore’s 25th anniversary at the Weather Channel (TWC). TWC has posted a video in which Cantore reflects on his career. The network will honor him on-air at 7 p.m. tonight.

Jason is the Washington Post’s weather editor and Capital Weather Gang's chief meteorologist. He earned a master's degree in atmospheric science, and spent 10 years as a climate change science analyst for the U.S. government. He holds the Digital Seal of Approval from the National Weather Association.


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