East Coast braces for record July Fourth heat as heatwave peaks

A dangerous heat wave tightens its grip on the East Coast just as the July Fourth weekend begins, with Washington, DC, and cities from NYC to Boston forecast to reach the upper 90s to low 100s and humidity pushing heat indices to 110F or higher. The National Weather Service says more than 160 million people are under major-to-extreme heat risk through the week, driven by persistent heat domes and climate warming. Cities are expanding cooling centers, shortening parade routes, and deploying hydration and medical resources as holiday crowds gather; energy regulators have ordered increased power generation to prevent outages on the PJM grid. Nights will be humid with little relief, and several cities could break temperature records, though some Midwest relief is possible later in the weekend, while the South remains hotter than normal into next week.