The heat index, or how it feels with humidity factored in, will rise into the triple digits for millions as the hot dome of high pressure engulfs the central states and eventually spreads eastward.

You’ll hear the term “heat dome” a lot this week as a pattern of very hot temperatures and dangerous heat indices set up across a good portion of the US. A heat dome is strong area of high pressure and warm air that essentially sits over an area for a prolonged period

While Texas bakes under sweltering conditions, it's far from alone. Millions are under threat of extreme heat this week.

More than 97 million people are under life-threatening heat alerts from the South to the East Coast as a large ridge of high pressure builds over the central U.S. this week, commo

Heat domes are caused by high-pressure systems that trap air near the surface of the Earth, sealing in hot, humid air and stopping cooler air from cycling through.

A heat dome dries out the ground and air above it, which deters thunderstorms, but means drought can begin or worsen. A heat dome is also known as a ridge of pressure, blocking high and death ridge.

The big weather story this week is a large area of high pressure building over the central U.S., often called a “heat dome,” the FOX Forecast Center warns.

Forecasters across the nation are saying that the heat is on through the end of July as temperatures in the East and Midwest are expected to reach triple digits while possibly lingering into August.

As it gets hotter, the risk continues to increase − potentially resulting in heatstroke or even death. Older adults, children, and outdoor workers are generally at higher risk of heat-related incidents.