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

Record-smashing daytime temperatures near 100 degrees are expected for millions from the Plains to the East Coast this week, while nighttime temperatures may stay above 80 in some metropolitan areas.

Tens of millions of people across the Midwest and East endured dangerously hot temperatures again on Sunday as a rare June heat wave that gripped much of the U.S. was expected to last well into this week.