A prolonged and dangerous heatwave is intensifying across parts of the central and eastern United States, bringing record-breaking temperatures and hazardous conditions to millions as the Fourth of July weekend approaches. The National Weather Service (NWS) warned on Thursday that temperatures between 95F and 105F, combined with high humidity, will push heat index values to between 100F and 115F across the region.
Record Temperatures Expected
The NWS stated that numerous daily temperature records are expected Thursday through Saturday, with some monthly and all-time records possible. The extreme heat will persist through Friday across the Midwest and Mississippi Valley, and linger through Independence Day weekend across the Ohio Valley and East Coast.
Weather officials emphasized that prolonged periods of extreme heat are among the deadliest weather hazards in the US because impacts build over time. They urged the public to limit time outdoors, stay hydrated, and ensure access to air conditioning or cooling centers.
Heat Warnings Across Multiple States
As of Thursday morning, areas across the Mississippi Valley, Great Lakes, Ohio Valley, and Northeast are under extreme heat warnings. In New York, temperatures are forecast to climb to around 100F on Thursday, with heat index values reaching as high as 115F through Saturday. Forecasters also warned of isolated to scattered thunderstorms each day through Sunday, with potential for damaging winds, large hail, and localized flash flooding.
New York City Mayor Zohran Mamdani urged residents to remain vigilant. “Please stay prepared and informed as these dangerously high temperatures continue,” he said, adding that Friday’s heat index was expected to reach 110F. “Plan for extreme temperatures. Drink more water than usual. Reach out to vulnerable neighbors who may need help finding resources.” The city is deploying cooling vans staffed with medical personnel to provide wellness checks, medical care, water, and transport to cooling centers.
Mid-Atlantic and Washington DC
Across the Mid-Atlantic, heat indices up to 110F are possible on Thursday, with showers and thunderstorms expected Friday and Saturday. Washington DC Mayor Muriel Bowser urged residents to factor the heat into their Fourth of July plans. “Consider the heat as you make plans for the 4th of July and America250,” she said, encouraging monitoring of weather alerts.
In parts of New Jersey and Philadelphia, Thursday and Friday are expected to be the hottest days, with dangerous heat continuing through Saturday. Philadelphia organizers shortened the route for the city’s Salute to Independence Semiquincentennial Parade due to the extreme heat.
Boston and Nationwide Impact
Emergency responders in Boston reminded residents that extreme heat can affect anyone. “During a heat wave, Boston EMS typically sees a 10–15% increase in 9-1-1 calls, with patients of all ages experiencing heat-related illness,” they said. “Stay somewhere cool, drink plenty of water and we’re here if you need us.”
This heatwave follows record-breaking high temperatures in Europe just days earlier, highlighting a pattern of extreme weather affecting multiple continents.
