A Punishing 'Heat Dome' Is Building in the U.S.

When your various sweat streams merge this week, creating a miniature Niagara Falls flowing directly into your pants, blame something called a “heat dome.”

The meteorological phenomenon, which will build through Friday, is expected to roast the Midwest, the northern/central Plains, and beyond with 100-plus degree temperatures. Taking the heat index into account, it might feel as hot as 110 or above. “Nighttime conditions will remain warm and muggy,” says the National Weather Service, “providing little chance for relief.” The worst of the roasting is likely to fall on Thursday and Friday, adds the service, which is cautioning people against going outside during the afternoon. (And seriously, think twice about hiking—that’s what killed several people during last month’s heat wave in Arizona.)