The intensifying and expansive heat wave affecting around 150 million people in the United States from Wisconsin to Washington, DC, bears the hallmarks of human-caused global warming.

The thermometer of a drugstore shows the temperature of 39 degrees Celsius (102 degrees Fahrenheit) during a heat wave, in Rome, Tuesday, July 1, 2025.

Heat wave incoming: How high will temps go and when will it end? A dangerous, widespread heat wave will bake the central and eastern U.S., bringing the hottest temperatures of the year and ...