Tens of millions of people across the Midwest and East are enduring another sweltering day of dangerously hot temperatures as a sprawling June heat wave grips much of the U.S.

A multiday heat wave is bringing high temperatures and health risks from the Midwest to the Northeast, prompting warnings and emergency measures.

Nearly 151 million people were under heat alerts from Colorado to Maine on Saturday, with major cities like New York City, Washington, D.C., Denver and Chicago set to be directly impacted with life-threatening temperatures.