The National Weather Service has 38 heat advisories in effect Sunday across 14 states, stretching from the high plains of Wyoming and South Dakota to the deserts of Nevada and Arizona and the Gulf Coast of Louisiana and Florida, as a broad ridge of high pressure locks dangerous heat over much of the West and South.
The most acute numbers are coming out of Colorado’s Front Range, where the Weather Service says temperatures will reach 98 to 104 degrees Sunday and Monday, with overnight lows only dropping to 65 to 72 degrees Sunday night — offering little relief before the heat rebuilds. The advisory there runs from noon Sunday to 9 p.m. MDT Monday and covers Denver weather, Boulder weather, Fort Collins, Castle Rock, Briggsdale and Greeley, along with Larimer, Boulder, Jefferson, Douglas, Adams, Arapahoe, Weld and Broomfield counties.
In South Dakota, the Weather Service is warning of heat index values up to 105 degrees across the northwestern and southwestern parts of the state, including the Rapid City area, Pennington and Custer counties and the Black Hills foothills, in an advisory running from 10 a.m. to 8 p.m. MDT Sunday. Wyoming’s advisory zone spans from Jackson Hole and the Wind River Basin to the Bighorn Basin, and continues into Utah’s Uinta Basin, Castle Country and the Great Salt Lake Desert.
In New Mexico, forecasters expect highs up to 100 degrees across the Northwest and West Central Plateau, with the advisory running from noon today through 8 p.m. MDT this evening. The Weather Service added a specific caution for the Gallup and Zuni Pueblo areas, where crews and residents are still engaged in flash flood recovery work and face added risk from combining heat exposure with that outdoor labor.
The advisories also extend into Alaska, Arizona, California, Idaho, Montana, Nevada and Texas, underscoring how widespread the heat has become rather than confined to a single region. The Weather Service’s standard guidance applies broadly: drink plenty of fluids, stay in an air-conditioned space when possible, avoid direct sun exposure, wear lightweight and loose-fitting clothing, and check on relatives and neighbors, particularly those without reliable air conditioning.
Heat remains the leading weather-related killer in the U.S. in most years, and forecasters note that overnight lows failing to drop much below 70 degrees in places like the Front Range compound the risk by preventing the body from recovering between hot afternoons.