The heat dome that turned the Fourth of July into one of the hottest holidays in years is finally starting to loosen its grip, and as it does the record tally is coming into focus. Across the eastern half of the country, hundreds of daily temperature records were tied or broken over the past week, a run of heat that the National Weather Service had warned would be historic and, by most measures, was.
The standout readings clustered in the Northeast corridor. Newark hit 105 degrees, a mark the New Jersey city had not reached since 2001; Atlantic City also touched 105; and Georgetown, Delaware, and Baltimore's Inner Harbor climbed to 104 and 103. Philadelphia and Washington spent the holiday at or just below their daily records, and cities from Boston south lived for days in triple-digit heat-index conditions as humidity layered onto the raw temperature.
The scale is easier to read against The Fold's own earlier coverage. When the ridge first took shape on June 29, forecasters were warning that close to 200 million people could be exposed as it expanded eastward. As the heat settled in, the National Weather Service refined its alerts, and by the holiday weekend roughly 185 million people sat under active advisories, watches or warnings — a slightly smaller headcount than the early projection, but concentrated over the humid Northeast and Ohio Valley where the heat was most dangerous.
What made the stretch hazardous was its persistence rather than any single peak. A large share of the records that fell were not afternoon highs but overnight lows — nights that never dropped far enough to let bodies, buildings and the power grid shed the day's heat. Utilities across the eastern grid reported record or near-record electricity demand as air conditioners ran around the clock, the kind of sustained load that stresses the system far more than a brief spike.
Relief is now in sight. Forecasters expect a shift in the jet stream to push the dome back toward the Plains early this week, allowing cooler, less humid air and more frequent thunderstorms to spread into the East. The mid-Atlantic and Northeast should feel the change by Monday or Tuesday, ending a heat event that will be remembered less for how hot it got than for how long it refused to break.
The pattern is not finished with the country, only relocating. As the ridge retreats west it is expected to rebuild over the Plains, meaning the same air mass that broke records in the East will keep temperatures well above normal across the middle of the country even as the coasts cool. For the eastern cities that spent the holiday under warnings, though, the worst of the 2026 heat dome now appears to be in the rearview.