‘Extremely high’ rates of heat-related ER visits, CDC says, with more coming Saturday

By Meteorologists Briana Waxman, Mary Gilbert, with Kate S. Petersen reporting

(CNN) — The deadly, multiday heat wave tightened its grip on the eastern United States on Friday, breaking records, sending people to the emergency room and raising the risk for millions of people starting to celebrate the Fourth of July outdoors.

More than a dozen locations in the Mid-Atlantic and Northeast broke or tied their high temperature records for Friday, including Washington, DC. The capital hit 102 degrees, surpassing the 101-degree record set in 1872.

The most extreme heat shifts a bit south on Saturday, staying high for DC with a forecast high of 102 degrees, which would make it the hottest July Fourth in the city’s history. Philadelphia and New York City are expected to be near 100 degrees with heat indices near 105.

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• Heat-related illness and death: A 68-year old man died after trimming bushes on July 2 in Bethel Township, Pennsylvania, where high temperatures passed 100 degrees, the Berks County Coroner’s Office told CNN. The cause of death was a heart attack from strain “due to heat exhaustion,” the office said. Meanwhile, the CDC reported “extremely high rates of heat-related illness” in regions across the Northeast on Thursday.

• Events canceled or delayed: The July Fourth parade set for Saturday morning in Washington, DC, was canceled due to extreme heat in the nation’s capital. President Donald Trump’s Great American State Fair is opening two hours late at 12 p.m. Philadelphia canceled its Friday Independence Day parade, which was expected to be one of the nation’s largest this holiday weekend, with participants from every state.

• NYC power outages: Thousands of customers in the New York metro area were without power Friday, according to local utility Con Edison. Some of the outages were shutdowns to prevent extended outages. Voltage reductions were also happening earlier in the day in parts of Staten Island, Queens, the Bronx, Brooklyn and Westchester, Con Edison spokesperson Jamie McShane told CNN.

• Pollution-fueled heat wave: The intensity of the heat and humidity combined this week would have been “virtually impossible” without the effects of fossil fuel pollution, according to an analysis from World Weather Attribution.

More than 20 cities broke records on Thursday, and several were hotter than Phoenix, the southwestern desert city known for breathtaking heat. DC, Philadelphia, Boston and parts of New York City all hit triple digit temperatures again on Friday afternoon.

The combination of heat and humidity is making conditions feel even hotter, with heat index values — what the air actually “feels like” to the body — forecast to climb even higher than the actual air temperature.

Human-caused climate change is making this familiar summer weather pattern far more dangerous. The intensity of the heat and humidity combined this week would have been “virtually impossible” without the effects of fossil fuel pollution. The finding was published early Friday from World Weather Attribution, a scientific network which analyzes the role of climate change in driving extreme weather events.

Heat is the deadliest weather hazard in the US, and the high humidity increases the risk, keeping temperatures elevated and preventing sweat from evaporating efficiently, making it harder for the body to cool itself. Overnight lows are also hotter now than they were decades ago, making it harder for people to get respite and rest.

The risk can build quickly, especially for older adults, children, outdoor workers and people without reliable access to air conditioning. Anyone heading outside for the holiday weekend should plan for frequent breaks indoors or at least in the shade. Drink water often, avoid intense activities and never leave children or pets in parked cars.

Heat strains power grid

As homes and businesses crank up air conditioning to stay cool, demand for electricity is surging.

Energy Secretary Chris Wright directed data centers in the Mid-Atlantic this week to use their backup power supplies instead of using electricity from the public grid, in part to ensure there was enough to power residential air conditioning.

Wright’s Tuesday orders were directed at data centers and other large electricity customers served by PJM, the country’s largest electrical grid operator. The PJM region is made up of 13 states. It is home to the world’s largest cluster of data centers in Virginia, and their dramatic energy use has led to serious electricity price spikes in certain Mid-Atlantic states over the past couple years.

Outside of the PJM grid, more than 19,000 Con Edison customers in the New York City metro area and stretching upstate lost power Thursday, according to the utility’s outage map.

“Heat, humidity, and increased demand for electricity to power air conditioners” are putting additional strain on Con Edison’s system primarily in the Bronx and Queens, the company said in a Friday news release. “Con Edison crews have restored service to more than 60,000 customers affected by scattered outages since the intense heatwave began.”

Mayor Zohran Mamdani posted on X to ask residents to set their AC to 78 degrees and unplug appliances to help conserve electricity and reduce the load on the grid.

Managing the holiday heat

Many cities, including Boston, New York, Philadelphia, Washington, DC, and Raleigh, North Carolina, are opening cooling centers and expanding public resources as the dangerous heat settles in.

Washington, DC, has activated an extreme heat alert through July 5 and is expanding cooling centers, hydration stations and emergency medical resources as hundreds of thousands of visitors descend on the nation’s capital for holiday events. Organizers of National Mall celebrations are adding water stations, cooling tents and air-conditioned buses for attendees.

New York City opened hundreds of cooling centers and deployed mobile medical vans to provide water, sunscreen and wellness checks. More than 2,200 LinkNYC kiosks are displaying directions to the nearest cooling center.

Philadelphia has declared a heat health emergency through Sunday evening. A ceremony featuring a live virtual address from the pope has been moved indoors, and officials have reduced hours for the city’s World Cup fan festival ahead of Saturday’s match between Paraguay and France. Event organizers have also canceled Fourth of July and World Cup block parties.

Amtrak has canceled at least 26 trains in the Northeast since July 2, including trains servicing major East Coast cities such as Baltimore, Philadelphia, New York City, and Boston. These cancellations are due to “temperature-related conditions,” Amtrak noted in posts on X.

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CNN’s Andrew Freedman and Vivien Williams and CNN Meteorologists Chris Dolce and Dakota Smith contributed to this report.