Yet another heat wave scorched the Western United States on Saturday, bringing extreme heat warnings to Southern California and record temperatures in the Southwest and Montana.
Wildfires erupted in the Pacific Northwest as the region faced an exceptionally rare “Particularly Dangerous Situation” warning due to extremely dry conditions and strong winds.
Phoenix reached 116 degrees Saturday afternoon, tying the region’s record for the hottest temperature ever recorded on the date Aug. 1, set in 1972, according to the National Weather Service. It was 6 degrees short of the area’s all-time record.
Las Vegas and El Centro, Calif., were within striking distance of their daily records, and both Great Falls and Helena, Mont., surpassed their daily records in preliminary measurements.
Officials in Southern California cautioned residents to look out for signs of heat-related illness, such as dizziness, confusion, headaches and nausea.
Extreme heat is one of the deadliest climate risks facing California. On the hottest days, heat-related illness can account for nearly 1 in every 100 emergency department visits in L.A. County. In 2025, the county recorded 10 heat-related deaths, according to a new dashboard.
Multiple days of high heat — with little relief overnight as temperatures remain high — can increase the risk.
“We’ve had these elevated temperatures for the last several days here, and that compounding effect can be significant,” said Rose Schoenfeld, a meteorologist with the National Weather Service. “We have some elevated humidity across the area that increases those overnight low temperatures a bit as well.”
The National Weather Service recommends limiting outdoor activity to the early hours of the day and staying in air-conditioned spaces during the afternoon and evening. It further advised residents never to leave pets or children unattended in vehicles, and to check in on loved ones.
The Pacific Northwest, which has had dozens of wildfires burning for days, saw a surge of activity Saturday afternoon into evening amid the National Weather Service’s strongest form of wildfire weather warning.
The Old Trails fire, sparked around noon, grew to more than 2,300 acres by 5 p.m., prompting evacuations in Spokane, Wash., according to the disaster tracking nonprofit Watch Duty.
Southern California’s heat warnings were set to expire Sunday night, with Schoenfeld noting the heat wave was expected to weaken Sunday into early next week.
The high temperatures are the result of a high-pressure system lingering over the area. As the air’s pressure increases, it heats up. The high pressure also stifles the sea breeze that can bring cooler ocean air onto land. Meanwhile, the region’s sticky humidity is thanks to an airflow pattern bringing moist, tropical air to Southern California.
