Dangerously high temperatures are threatening much of the US northeast and deep south as huge swathes of the country swelter under a heatwave that could continue for days.
As some temperatures neared 37.8C on Thursday, millions of Americans sought comfort by staying in the shade of homes or in air-conditioned offices, and cooled themselves in fountains, at beaches or in cooling centres.
The heat is expected to extend into the weekend, prompting officials to urge people to seek shelter as well as drink lots of water and check on elderly neighbours for signs of distress.
In the New York City area, temperatures would again soar into the 30s but the high moisture in the air would make it feel even hotter, meteorologist James Tomasini said.
Excessive heat warnings - issued when the heat index surpasses 40.6C continuously for at least two hours - were in effect in parts of the deep south and pockets of the mid-Atlantic.
Heat advisories extended along the east coast, from South Carolina to southern Maine.
In Boston, residents and visitors were doing their best to cool down during the third of what could be a six-day stretch of temperatures well into the 30s.
Mayor Michelle Wu extended a previously announced heat emergency in the city through Sunday and urged resident to take advantage of cooling centres and splash pads.
In the Tidewater area of southeast Virginia, temperatures were expected to reach nearly the century mark, but humidity would push the heat index beyond 40C, meteorologist Tim Gingrich said.
This summer is shaping up to be one of the hottest on record, not just in the United States but across Europe and other parts of the globe.
Australian Associated Press