It looks like the sky will generally cooperate for eclipse viewing this afternoon. High pressure to our south should keep the skies mostly clear today. There is a slight chance we could see a few thin cirrus clouds as a result of afternoon storms over Pennsylvania and a chance of some sea breeze-induced cumulus clouds inland from south-facing beaches.
The map above shows calculated incoming sunlight at 3 p.m. The big white void off the South Carolina coast is the area of the total solar eclipse. The little white blotches around New York are place locations, not clouds. At the peak of the eclipse, around 2:44 p.m. we will only see about 200 Watts of sunlight per square meter, which is about a third of what we'd get on a sunny late-August day and equivalent to what we'd see on an overcast day.
Despite the interruption in sunshine today's high will be in the mid to upper 80s. Those storms over Pennsylvania will move eastward overnight so we could see a few showers after midnight. The heat and humidity will build up tomorrow as the high moves offshore. Look for a high near 90 and a slight chance of showers or thunderstorms. Cooler, drier weather will arrive following the passage of a cold front late Tuesday, with sunny and mild conditions expected from Wednesday through the weekend.