A dangerous heat wave is tightening its grip on the East Coast, with the worst conditions underway as millions prepare to celebrate the Fourth of July outdoors.

A prolonged, dangerous heat wave will continue to intensify across most of the central to eastern U.S. into the Fourth of July weekend.

The nation is gripped in a dangerous heat dome. Threatening millions of people in the Midwest and Eastern United States.

High humidity is expected to make conditions feel even hotter

Dangerous heat wave threatens U.S. Fourth of July celebrations-