It’s still relatively early in the summer season in the Northern Hemisphere, but several parts of North America were sweltering in mid-July.
The latest purveyor of heat was a strong ridge of high pressure that lingered in the upper atmosphere over the northern Rockies on the weekend of July 11-12, 2026. This pushed hot air toward the surface and trapped it there—a weather phenomenon meteorologists call a heat dome.
Heat domes put the brakes on convection and suppress clouds and precipitation. This allows sunlight to reach Earth’s surface relatively unhindered and further elevate air temperatures. As a result of the July heat dome, sites in Montana, Wyoming, and Utah broke all-time temperature records.
The map above shows air temperatures across the United States on July 12, 2026, at 2 p.m. Mountain Time, modeled at 2 meters (6.5 feet) above the ground. It was produced by combining satellite observations with temperatures predicted by a version of the GEOS (Goddard Earth Observing System) model, which uses mathematical equations to represent physical processes in the atmosphere. The darkest reds indicate areas where temperatures approached or exceeded 45 degrees Celsius (113 degrees Fahrenheit).
A preliminary analysis from the National Weather Service office in Billings found that temperature sensors at airports in Billings and Miles City, Montana (111°F and 115°F, respectively), and Sheridan, Wyoming (109°F), all recorded new all-time record highs on July 12. Each of these stations topped its previous record by at least 2°F, with Miles City breaking its record by a full 4°F. The Montana records date to the 1930s; the Sheridan record begins in 1907.
Multiple locations in Utah broke all-time records as well, according to the National Weather Service office in Salt Lake City, including Deseret (111°F), Salt Lake City (109°F, or 4°F above the previous record), and Randolph (100°F, or 6°F above the p …