An intense heat wave spread across parts of the western and central United States on Saturday, with triple-digit temperatures forecast from the Intermountain West into the Northern Plains and dangerous heat and humidity lingering in parts of the Southeast.

Most of America’s Lower 48 states are about to swelter under an unusually large, strong and long-lasting heat dome.

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