A “significant and extremely dangerous heat wave” is expected to send temperatures soaring across much of the United States in the coming days, stretching from the Central Plains to the East Coast, according to forecasters with the Weather Prediction Center.

Millions of Americans are facing oppressive heat, with forecasters expecting a "heat dome" to develop over parts of the county over the weekend and through next week. The National Weather Service (NWS) warns that heat related illnesses increase significantly during extreme heat events.

Some parts of the U.S., such as Phoenix, Arizona, are famously hot without the mugginess. Phoenix and nearby desert regions experience this so-called “dry heat” due to being located far away from large water bodies, mountains that block moist air masses and weather patterns that bring scarce precipitation.