1. Get out the fans, seek cool refuge and drink plenty of water: A heat wave is about to affect millions of people across the U.S.

Dangerously high temperatures are forecast from Oklahoma to New England through the weekend. The middle of the country will see the worst of it: Kansas could hit 102 degrees.

The operative term: “heat dome,” a large area of scorching temperatures trapped by high pressure atmospheric conditions. Above, visitors keep cool under misters at the Phoenix Zoo.