A relentless heat dome has locked in over the eastern U.S., plunging tens of millions into dangerously hot conditions—and it’s only getting worse.
As of July 25, the East Coast is enduring the most intense heat, with over 80 million people facing major or extreme heat risks, according to the National Weather Service. That number is expected to climb to nearly 150 million—nearly half the U.S. population—by July 28, as the heat expands across the Southeast with several days of potentially record-breaking temperatures ahead.
“Even though it’s midsummer, this is pretty notable,” said Bryan Jackson, meteorologist at the NWS Weather Prediction Center.
Heat domes form when a high-pressure system traps hot air over a region, acting like a lid on the atmosphere. This setup leads to higher temperatures, clearer skies, and minimal rainfall. “It’s a cap on the atmosphere,” explained meteorologist Zack Taylor. And once in place, they tend to linger. “Heat domes are generally slow to form and slow to dissipate,” Jackson added.
This particular dome is expected to last longer than usual. While temperatures on the East Coast briefly spike on July 25, the dome will strengthen over the Southeast through July 31, bringing record heat to areas like Columbia, S.C., and Tallahassee, Fla. High humidity will keep nights uncomfortably warm, depriving residents of relief after sunset.
The National Weather Service’s HeatRisk map categorizes heat danger from minimal to extreme. On July 28 and 30, more than 24 million people will face extreme heat with no overnight relief. On July 29 alone, over 30 million will be under the highest risk category. Meanwhile, more than 100 million will experience major heat risk on July 28 and 29.
Heat remains one of the deadliest weather threats. In 2023, the CDC linked 2,325 deaths to heat—more than twice the number reported in 1999. With climate change intensifying, extreme heat events are becoming more frequent and severe.
If you’re in an affected area, follow science-based safety tips to protect your health and keep your home cool.
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Katie is a senior who has been on staff for three years. Her favorite type of stories to write is reviews and features. Katie’s favorite ice cream flavor is strawberry.
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