There's no relief yet from the heat wave that was set over most of the U.S. and made its way to Delaware. The National Weather Service has issued an extreme heat warning for nearly all of Delaware through Wednesday,

With a heat wave causing excessive heat warnings in Delaware, you'll hear a lot about the heat index this week. What to know and how to stay cool.

The official heat wave will begin today, following yesterday's fall just below the 90-degree mark, thanks to the spotty storms. Expect Monday to approach 100 degrees in many areas across the Delaware Valley,