Dangerous heatwave to hit US ahead of holiday weekend
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- The National Weather Service forecasts ~250 million people will face dangerous heat starting Thursday, with ~120 million already under extreme heat warnings as of Tuesday ahead of the Fourth of July holiday weekend.
- A heat dome will push temperatures to 95F–105F with heat indexes reaching 100F–115F, peaking Thursday in the Midwest and Mississippi Valley before shifting east to the Ohio Valley and East Coast; daily, monthly, and all-time temperature records could fall Thursday and Friday.
- New York City Mayor Zohran Mamdani activated a heat emergency plan with hundreds of cooling centres opening Wednesday, while Detroit opened a dozen air-conditioned recreation centres as temperatures there could reach 100F.
- Canada's Ontario province is under orange heat warnings—the second-highest alert level—with temperatures expected to hit 37C (99F); Toronto is due to host a World Cup match Thursday when readings could reach 35C (95F).
- World Cup host cities in Houston, Arlington, and Atlanta—including Wednesday's England v DR Congo match—could see heat indexes exceeding the threshold where Fifpro considers conditions too unsafe for play, and Philadelphia is relocating parts of its Fan Festival into cooled tents Thursday and Friday.
Why it matters: With 250 million Americans facing dangerous heat and several World Cup host cities approaching the heat-index threshold where Fifpro considers play unsafe, the heat dome forces public-health and sporting-safety officials into simultaneous emergency response across the continent.
