Some 200 cities in the West hit daily record highs last week, including Las Vegas at 117, and Death Valley soared to 129, the weather service said.

The blistering heat has caused numerous deaths this summer. In the Phoenix area alone, 24 people, most of them homeless, have died.

At least four deaths have been blamed on the heat in Missouri, including a woman found dead Sunday in a home without air conditioning. Four people have died of the heat in Oklahoma, two of them young children left in cars, and at least three heat deaths have been tallied in New Jersey.