Most of America’s Lower 48 states are about to swelter under an unusually large, strong and long-lasting heat dome that will spike temperatures in a way that the National Weather Service calls “significant and dangerous.”The heat wave will start this weekend and last at least a week, with some areas feeling its effects until the end of the month, meteorologists said. Temperatures will be 15 to 25 degrees Fahrenheit (8 to 14 degrees Celsius) warmer than normal in many areas, including at night, they said. Hotter nighttime temperatures are especially bad for both human health and efforts to tamp down an already active wildfire season.“This upcoming heat wave does look pretty remarkable,” said Daniel Swain, a climate scientist with University of California Agriculture and Natural Resources. “This is going to be a long duration, widespread and high-intensity heat event that’s going to affect millions of people for over a week.”Trapping hot air, threatening records
Mickelina Papotto, of Salem, Ore., left, and Lorie Odegaard, of Gaithersburg, Md., fan themselves while waiting in line for the ferris wheel at the Great American State Fair on the National Mall, July 1, 2026, in Washington. (AP Photo/Jacquelyn Martin)
