Some of the cameras show either a lot of fog or a lot of smoke. Earlier it really didn't look like fog because of how quick it was moving and it was not spread out like fog would be.
Live Webcam 1 - Reagan National Airport - Washington D.C.
Live Webcam 2 - 4K - Reagan National Airport - Washington D.C.
Live Webcam 3 - 4K - Reagan National Airport - Washington D.C.
https://forecast.weather.gov/MapClick.php?x=245&y=101&site=lwx&zmx=&zmy=&map_x=244&map_y=101
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