Heat wave's deadly impact grows
Extreme heat gripping much of the U.S. has killed at least two dozen people over the past week, as about 40 million people remained under heat alerts Sunday. Why it matters: Extreme heat is the nation's deadliest weather hazard, and the rising death toll underscores how dangerous prolonged heat can be. The big picture: A prolonged heat dome stretching from the Midwest to the East Coast has kept tens of millions under heat alerts and made the weeklong heat wave one of the summer's deadliest weat…

