Strong heat dome set to bring record temperatures to western United States
A powerful heat dome will drive temperatures 10-20°F above normal across the western U.S. this weekend, affecting millions and prompting extreme heat alerts.
A high-pressure system expected to linger over the western United States this weekend will push temperatures 10 to nearly 20 degrees Fahrenheit above normal from Southern California to the northern Rockies and Plains, according to the National Weather Service. Forecasts call for Death Valley, California, to reach 126°F, the highest temperature of the current heat wave.
At least 12 states are projected to see dozens of record-high readings, with roughly 40 million people under heat alerts. More than 12 million residents in the Southwest, Mountain West and northern Great Plains face a Level 4 “extreme” heat risk on Saturday and Sunday, while an additional 12 million are under a Level 3 “major” risk.
The heat dome, described by meteorologists as a slow-moving ridge that traps warm air, may set new intensity records in parts of Southern California and Arizona. Overnight lows are also expected to remain about 10°F above normal, limiting nighttime relief.
Cities such as Billings, Montana, and Salt Lake City are forecast to break August temperature records, with highs near 106°F. Phoenix, Tucson and Las Vegas are projected to exceed 110°F. The National Weather Service notes that heat is the leading cause of weather-related fatalities in the United States, and emergency rooms typically see a surge in heat-related illnesses on extreme-risk days.
The elevated temperatures are expected to exacerbate existing wildfire and water-resource challenges. Reduced snowfall in the Colorado River Basin and historically low levels in Lake Mead and Lake Powell could accelerate evaporation and strain water supplies for tens of millions of people.
Authorities advise residents to stay hydrated, seek cooling centers where available, and limit outdoor activity during peak heat hours.