Thunderstorms are set to batter July 4 celebrations in Washington, DC, and New York as a waning heat dome continues to test electricity grids in the eastern U.S., following record power demand over the past few days.
Storms will likely move through the U.S. capital on Saturday night, helping to cool temperatures to lows of about 75 degrees, according to a forecast from the National Weather Service made shortly before 5 p.m. Eastern. Highs in Washington on July 4 were near 103 degrees, and about 94 degrees in New York.
“Thunderstorms could very well be severe with damaging wind gusts looking to be the primary threat with them, and of course lightning,” said Joe Wegman, a forecaster at the U.S. Weather Prediction Center. “Until those storms arrive, the heat is still very much on. So we want to take all precautions.”
The lingering heat is likely to continue straining power grids in the east of the country. PJM Interconnection LLC, which serves 67 million people across 13 states, likely surpassed on July 2 the previous record of 165.563 gigawatts set in August 2006. The longer temperatures stay high, the greater the risk that electrical equipment, such as transformers, begin to fail.
Consolidated Edison Co. which runs New York City’s electric utility, has asked around 163,000 customers in southeastern Queens to conserve energy while equipment repairs take place. It said it would distribute dry ice to those that had lost power during the heat wave.
About 130 million people from Texas to New Hampshire faced either heat advisories or extreme heat warnings on Saturday. The most intense heat is set to gradually shift southward from the Ohio Valley and Northeast into the southern Mid-Atlantic and Southeast late this weekend and into early next week, the National Weather Service said.
As the heat retreats, the threat of thunderstorms will rise.
“Storms will follow late tomorrow, too – with the most severe in South Jersey,” New Jersey Governor Mikie Sherrill said on X, advising the state’s residents to monitor emergency alerts and guidance.
Storms on Friday night caused “severe damage” and left many without power and forced New Jersey Transit to suspend some lines, she said in a separate post. Amtrak trains were also slowed, while high temperatures and oppressive humidity put a crimp on U.S. Independence Day celebrations and World Cup matches on Friday.
The Great American State Fair — a two-week festival being staged on the National Mall in Washington — closed for several hours Friday as temperatures soared.
Clusters of storms will continue to move across parts of the Allegheny Plateau into the Mid-Atlantic, with potential for numerous damaging wind gusts, the U.S. Storm Prediction Center said.
There were 400 reports of high winds and hail across the U.S. on Friday, with many of them in a band stretching from Chicago to New York, the agency said.
From Missouri to Long Island, more than 800,000 homes and businesses were without power as of 5:27 p.m. New York time, according to the PowerOutage.com. Michigan topped the list of states suffering blackouts with more than 300,000, followed by New Jersey with more than 140,000.
Even before the latest bout of intense heat, U.S. grids were struggling with data center buildouts that have upended two decades of stagnant power demand. And now they’re even more susceptible to outages in periods of extreme temperature fluctuations, with implications for everything from residential air conditioners to hospital lighting.
The worst of the heat sparking warnings and advisories will subside Saturday night across the Northeast and Mid-Atlantic, according to forecasters. Power prices in PJM had calmed Saturday after peaking above $2,500 per megawatt hour multiple times this week in the region that is home to “data center alley” in Northern Virginia.
Manhattan’s Central Park is likely to see a 25 degree swing in high temperatures from Thursday — when a record 100 degrees reading was posted for the date — to Monday, when the forecast calls for near 75 degrees.
(With assistance from Lauren Rosenthal and Naureen S. Malik.)