The brutal heat is being blamed for as many as a dozen deaths across the country. Twenty states from Texas to Minnesota are under a heat watch, warning, or advisory.
The heat index broke the 100 degree barrier in many places, but the hottest was Newton, Iowa, where the combined heat and humidity made it feel like 126 degrees.
Almost three-quarters of Texas is locked in an exceptional drought.
And in neighboring Oklahoma, authorities are considering water restrictions. Tulsa set a record for water use on Saturday -- using more than 200 million gallons.
In Minnesota, the extreme heat buckled a major interstate, stranding thousands of travelers.