More than 100 million Americans are being warned to stay indoors if possible as a heat wave settles over states stretching through parts of the Gulf Coast to the Great Lakes and east to the Carolinas.

The National Weather Service Prediction Center in College Park, Maryland, said Monday that a combination of heat advisories, excessive heat warnings and excessive heat watches will impact 107.5 million people, and record-setting temperatures are expected to last through midweek.

St. Louis, Memphis, Minneapolis and Tulsa are among several cities under excessive heat warnings, with temperatures expected to reach above 100 in some areas. High humidity is forecast to accompany the heat, adding to the dangerous conditions.