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

Cities across the eastern and central United States are bracing for more days of extreme temperatures as a unusual June heat wave continues to grip that portion of the country.

The temperature made it to 91 on Saturday in Philly, and by the end of the workweek, that kind of heat may seem like a cool shower. By then, said Zack Taylor, chief of the analysis section at the National Oceanic and Atmospheric Administration’s Weather Prediction Center,