 Tens of millions of people this weekend set to be exposed to searing heat, says ABC's Jacqueline Lee. A historic heat wave searing the West, 158 million people under heat alerts. Well, we want to make sure that they're staying indoors between the hours of 10 and 3, stay hydrated and rested. Death Valley could clock a scalding 129 degrees, just 5 degrees shy of the hottest temperature ever recorded on Earth.