Before it gets better, "the record heat wave" could get worse. The National Weather Service forecasts "the heat will begin to expand eastward over the next few days, with high temperatures and humidity levels combining to create dangerous heat index values in the triple digits."

Some relief could come "by week's end," when the Upper Midwest should cool as a cold front moves across the Great Lakes. By Monday, that could mean a 20-degree drop in some places.

The storms left at least 22 people dead from Ohio to New Jersey -- 13 of them in Virginia. An additional three people in North Carolina died in a second round of storms Sunday.