Severe thunderstorms could continue into July 29, bringing havoc to morning commutes in Chicago, Milwaukee and Indianapolis.

Temperatures are expected to fall into the 70s by the weekend. But first, multiple rounds of storms are possible in Kansas City

More than 250 million people in the U.S.—nearly three quarters of the population—are experiencing moderate, major or extreme risk of heat effects on July 28, according to the National Oceanic and Atmospheric Administration’s National Weather Service.

High pressure will continue to build west over North Texas tomorrow, keeping temperatures near 100 degrees. A weak front will sag south from Oklahoma Thursday evening into Friday and stall out, keeping low rain chances in the forecast into the weekend along with cooler temperatures.

Heat stroke differs from heat exhaustion in two major ways, Smurawa said. Heat stroke involves a dangerously high core body temperature — typically 104 F or more — and can impair the central nervous system. This means a person may become disoriented, confused or, in severe cases, experience seizures or even coma.

Heat index values could reach as high as 106. Temperatures are expected to cool down later this week. Here's what to know about the forecast.

On Tuesday, the heat turns up even more with high temperatures across the region likely in the mid-upper 90s. The forecast for Tuesday and Wednesday in Philadelphia is for a high of 98 degrees, which would tie the record for both days.