 On top of that, we have an excessive heat warning for the metro, and that means heat index values around 100 to 110 degrees. In terms of the storms, the greatest chance is going to be around dinnertime into early evening. Could be looking at some gusty winds, heavy downpours, and can't rule out a quick, weak tornado. D.C. activated its heat emergency plan again today. That means cooling centers and spray parks are open across the district. There are also cooling centers in Fairfax, Loudoun, and Prince George's County.