New York City activates emergency plan as heat dome threatens triple-digit temperatures across US East Coast

A dangerous heat dome is expanding across the central and eastern United States, bringing triple-digit temperatures and extreme humidity to tens of millions of people. The National Weather Service warns of dozens of local temperature records falling, with heat indices reaching up to 115°F (46°C). New York City, Washington D.C., and other major cities are activating emergency plans as the heat wave coincides with World Cup matches and Independence Day celebrations.

Heat dome intensifies

The heat dome, a sprawling area of high pressure trapping hot air, settled over the Tennessee Valley early Tuesday and is forecast to expand to the Mid-Atlantic by the weekend. More than 60 million people are under heat alerts, and the Washington Post reports that 73 million Americans will experience triple-digit heat through Sunday, with 190 million facing extreme humidity and 205 million at major or extreme risk of heat-related impacts through Monday, according to NOAA's HeatRisk.

This is Texas hot, which we don't usually see here, so it's serious.

New York City's emergency response

Mayor Zohran Mamdani, drawing lessons from a deadly winter blizzard, has activated what City Hall calls an "unprecedented, historic heat emergency plan." The city is opening about 600 cooling centers in libraries, senior centers, and other air-conditioned spaces, and deploying 15 outreach vans staffed by nurses to provide wellness checks and emergency transport. Pop-up cooling stations with misting fans and cold water are being set up for outdoor workers, including street vendors and delivery drivers. An executive order signed last week aims to strengthen workplace protections for the estimated 93,000 people who work outside.

We are possibly facing the second hottest day in New York City history in more than a decade — life-threatening heat.

Records poised to fall

Meteorologists are watching several temperature milestones. New York City could hit 100°F for the first time in 14 years, with forecasts of 101°F on both Thursday and Friday. Washington D.C. is predicted to reach 100°F or above on Thursday, Friday, and Saturday, potentially tying its record of four consecutive 100-degree days. Philadelphia may tie its record of three straight 100-degree days. More than 100 daily high records and over 200 nighttime records are expected to be broken from Texas to Maine.

It's really just about simple matters of probability.

World Cup and July 4th celebrations impacted

The heat wave coincides with the knockout stage of the World Cup, co-hosted by the United States, Canada, and Mexico. FIFA has introduced hydration breaks, and matches like France vs. Sweden at New York New Jersey Stadium (which has no air conditioning) and Norway vs. Côte d'Ivoire in Dallas are being played in oppressive conditions. Two group-stage matches already exceeded the temperature threshold at which the global players' union recommends postponement, and dozens of fans have been treated for heat illness in Houston and Miami. Meanwhile, Washington D.C. is preparing for its biggest-ever fireworks display on the National Mall on July 4, with temperatures forecast at 100°F.

Health risks and safety measures

Health officials emphasize that overnight temperatures are especially dangerous. Ashley Ward, director of the Heat Policy Innovation Hub at Duke University, noted that when overnight lows stay above 75°F (24°C), heat illness and mortality rise sharply. The city is extending public pool hours and distributing spray caps for fire hydrants. Chicago is also opening cooling centers and conducting wellness checks. Authorities warn of heat-related illnesses and urge people to watch for signs of heat stroke. Nine child hot-car deaths have been reported this year, and pet owners are advised to keep animals indoors.