It’s still relatively early in thesummer seasonin the Northern Hemisphere, but several parts of North America were sweltering in mid-July.
The latest purveyor of heat was a strongridgeof high pressure that lingered in the upper atmosphere over the northern Rockies on the weekend of July 11-12, 2026.
This pushed hot airtoward the surfaceand trapped it there—a weather phenomenon meteorologists call aheat dome.
Heat domes put the brakes onconvectionand 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 above the ground.
It was produced by combining satellite observations with temperatures predicted by a version of theGEOS 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.
Apreliminary analysisfrom the National Weather Service office in Billings found that temperature sensors at airports in Billings and Miles City, Montana, and Sheridan, Wyoming, 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, accordingto the National Weather Service office in Salt Lake City, including Deseret, Salt Lake City, and Randolph.
These stations in Utah have records that date back to the 1890s.
Extreme heat doesn’t just make people uncomfortable.
It can have serious health consequences, particularly for older people.
Extreme heatworsens common age-related health conditions such as heart, lung, and kidney disease.
Health tracking datafrom the U.S. Centers for Disease Control and Prevention shows that the rate of heat-related emergency department visits in the Mountain states spiked tenfold during the July heat.
Heat waves like this one have become more frequent in the United States in recent decades, according to researchers at NASA’s Goddard Space Flight Center.
Using a NASA modeling system calledMERRA-2, oneNASA team foundthat summer heat waves in the U.S.roughly doubledin number between 1980 and 2023, increasing from an average of two to four per month.
Forecastersexpectthe heat dome to spread east into the Midwest, New England, and the Mid-Atlantic in the coming days, where triple-digit temperatures are likely in some areas.
The United States isn’t alone in facing significant heat.
Parts of both Western Europe, Central Asia, and East Asiaare also facing heat waves.
NASA Earth Observatory image by Michala Garrison, usingGEOS-FPdata from the Global Modeling and Assimilation Officeat NASA GSFC. Story by Adam Voiland.
JPEG
AccuWeather‘Steam-cooker’ pattern grips the Central, East as heat and humidity peak. Accessed July 14, 2026.
NASARising Heat Waves in North America in the Past 40 Years. Accessed July 14, 2026.
NASA Earth ObservatoryGEOS-5: A High Resolution Global Atmospheric Model. Accessed July 14, 2026.
National Weather ServiceShort Range Forecast. Accessed July 14, 2026.
NOAARecord Heat Southern Montana July 12, 2026. Accessed July 14, 2026.
Royal Meteorological SocietyWhat is a heat dome? Accessed July 14, 2026.
U.S. Centers for Disease Control and PreventionDaily Heat-Related Illness. Accessed July 14, 2026.
U.S. National Weather Service, via FacebookYesterday was quite historic in terms of heat. Accessed July 14, 2026.
The Washington PostOne of the planet’s strongest heat domes will soon scorch the East Coast. Accessed July 14, 2026.
Stay up-to-date with the latest content from NASA as we explore the universe and discover more about our home planet.
Temperatures in several states climbed over 100 degrees Fahrenheit in March 2026, which in some places was the highest March…
Satellite observations of sea surface height indicated that the 2026 event continued to strengthen in early June.
Satellites observed striking upper-atmosphere phenomena generated by an intensifying tropical cyclone.
Subscribe to the Earth Observatory and get the Earth in your inbox.
NASA’s Earth Observatory brings you the Earth, every day, with in-depth stories and stunning imagery.
Explore Earth Science
Open access to NASA’s archive of Earth science data