St. Louis, Omaha and Des Moines were among the cities that saw heat indexes rise toward triple digits, with similar temperatures expected on the East Coast by Monday.

St. Louis, Omaha and Des Moines were among the cities that saw heat indexes rise toward triple digits, with similar temperatures expected on the East Coast by Monday.

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