Tens of millions of people across the Midwest and Mid-Atlantic are under heat alerts Monday as a dangerous heat wave that began over the weekend continues to move through the region.

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,

The National Weather Service issued an extreme heat warning for New Castle County lasting through June 25. See how hot Delaware will get this week.