San Francisco Frontiers - Dangerous heatwave hits peak temps along US east coast

With the heat index threatening to top 115F (46C), records could be broken in New York City, as extreme heat warnings blanketed the northeast and mid-Atlantic regions.

Combined with very humid air, the "feels like" temperature could reach 105F in Boston, 112F in Philadelphia, and 113F in Washington.

"Numerous daily temperature records are expected today and Independence Day, with some consecutive-day, monthly, and all-time records possible," the National Weather Service said.

Hang Dang, a 76-year-old retiree, was not letting extreme temperatures deter her from attending celebrations in Washington for the 250th July Fourth anniversary.

"I came to the US in 1975 from Vietnam and... I was here for the bicentennial," Dang told AFP, noting she drove 12 hours from Florida to attend festivities.

"I said I've got to get back for the 250th because I don't think I'll make it to the 300th!" she joked as a Marine Corps Osprey aircraft hovered nearby.

In New York, the most populous US city, Mayor Zohran Mamdani urged residents to "stay cool, stay vigilant and check in on your neighbors."

The city has transformed hundreds of public buildings into cooling centers, dispatched volunteers to check on vulnerable citizens, and extended the hours of swimming pools across the city.

- World Cup impacts -

Three World Cup matches were slated for Friday in the US, including in Miami where Argentina and Cape Verde face off at 6 pm. The stadium has no air conditioning and the heat index at kickoff was expected to hit 100F.

On Saturday, France and Paraguay will clash in Philadelphia where the heat index could reach 105F.

In response to concerns over heat, FIFA has introduced a mandatory "hydration break" in each half of every game at this World Cup, although it was not clear whether that would be adequate for matches taking place outdoors during the heat wave.

Although many buildings in the United States are air-conditioned, heat waves cause more deaths in the country than hurricanes and floods.

This particular heat wave is worrying because of its duration and intensity, but also because high nighttime temperatures could threaten vulnerable people and strain energy infrastructure.

On Thursday, Chicago utility company ComEd said its power grid was under "critical strain," and urged residents to "raise your thermostat as high as is comfortably safe."

The current extreme heat and humidity would have been "virtually impossible" without climate change, a study from the World Weather Attribution group of leading climate researchers said Friday.

- Heated celebrations -

In Washington on Friday morning, hundreds of people braved sizzling heat to visit the Great American State Fair taking place on the National Mall.

Many visitors told AFP they had altered their plans so they could avoid the afternoon sun.

"The problem here is that the heat builds," said Kevin Ashley of Alexandria, Virginia.

"In the afternoon it becomes really intolerable, because this is reclaimed swamp," he said, nodding to Washington's geography.

Nearby, crowds huddled in thin strips of shade outside pavilions, gulping free bottles of water that workers were distributing throughout the event.

Paramedics meanwhile carted away a young woman suffering from apparent heat exhaustion.

"It's like the 30th person," said an event staffer.

A short time later, organizers closed the fair until 5 pm.

"The safety and well-being of our guests, volunteers, performers, vendors, and staff is our highest priority," a spokesperson told AFP. "Conditions are expected to improve later this afternoon."

E.Cruz--SFF