Why heat wave warnings are falling short in the U.S.

In 1995, a heat wave in Chicago required morgue technicians use to rows of refrigerated trucks, after 1,000 people died the broader region. High humidity made the heat deceptively dangerous. (Mike Fisher/AP)

In July 1995, weather reports in Chicago started warning residents about an incoming heat wave. It was going to be hot – around 100 degrees – but nothing that was unheard of for a Chicago summer.

That heat wave turned out to be one of the deadliest in recorded U.S. history.