Where, when and how bad the Fourth of July heat wave will be, in seven diagrams, charts and maps

NBC News Clone summarizes the latest on: Us Extreme Heat Dome July Fourth 2026 Maps Charts Rcna352304 - Breaking News | NBC News Clone. This article is rewritten and presented in a simplified tone for a better reader experience.

More than 160 million people — nearly half the U.S. population — are under heat alerts Thursday.

People cool off along the lakefront as temperatures topped 90 degrees on June 29, 2026 in Chicago, Illinois.

People cool off along Lake Michigan as temperatures topped 90 degrees in Chicago on Monday. The city could reach a heat index of 101 degrees Thursday.Scott Olson / Getty Images

July 2, 2026, 2:18 PM EDT

By Joelle Gross, Jiachuan Wu, Javier Zarracina and Joe Murphy

The U.S. is looking at an unwelcome birthday gift: a dangerous heat wave arriving ahead of the holiday weekend.

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