Nationwide heat dome to push U.S. temperatures into danger zone through July Fourth

A dangerous heat wave fueled by a heat dome will sweep central to eastern U.S. this week, with daytime highs in the 90s to low 100s and humidity pushing heat indices to 100–110°F (locally up to 115°F). About 90 million people are under extreme heat alerts and up to 230 million could be exposed, with little overnight relief and the possibility of record highs; the heat dome is forecast to linger into the Fourth of July weekend, gradually easing from west to east afterward. Stay hydrated, stay cool, and check on vulnerable neighbors.