The National Weather Service has issued a Severe Thunderstorm Warning for northwestern Lancaster County and southwestern Lebanon County until 8:30 p.m.

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

Major cities under heat alerts Monday include Dallas, Oklahoma City, St. Louis, Chicago, Memphis, Atlanta, Tampa, Charleston, New York, Philadelphia and Boston.

Much of the U.S. is under extreme heat warnings or advisories while New York, Philadelphia and Washington DC could feel like 100 degrees or more.

Extreme heat is likely to break daily temperature records, but the weather forecast calls for a cool-down as August arrives.

A big change in the weather pattern will arrive in the Northeast around the same time the calendar flips to August. But ...

With the jet stream positioned well to the north, hot and humid conditions are forecast for millions in the Northeast through ...