The Western U.S. was bracing for record-high temperatures as a heat wave gripped large swaths of the region, prompting warnings for people to stay inside and heightening wildfire risks in areas that already are dry or burning.
A ridge of high pressure is holding heat close to the ground — what’s known as a heat dome — from Arizona to Montana, though the good news is that it will be relatively short-lived, National Weather Service meteorologists said.
Dangerous heat and warnings were plaguing the region Saturday, and the National Weather Service on Saturday forecast a high of 115 degrees Fahrenheit (46 degrees Celsius) in Las Vegas, the hottest temperature of the year. Phoenix was expected to reach 116F (47C), while El Centro, California, was expected to hit a record 118F (48C). Even parts of Montana were expected to broil, with a record 104F (40C) forecast for Great Falls.
In Las Vegas, Saturday's forecast high was 10 degrees above normal, with meteorologists warning of dangerous heat through Sunday, when the high is expected to be 114, said weather service meteorologist Morgan Stessman.
Overnight lows in the upper 80s to low 90s will make the situation especially dangerous because it doesn't allow people’s bodies to recover. “There's just no relief overnight,” Stessman said.
People were being urged to stay indoors and hydrated.
The August record for Las Vegas is 116F (47C), while the hottest on record was 120F (49C) in July 2024, which also was the hottest summer on record, Stessman said.
In Montana, the entire east side of the state was under an extreme heat warning Saturday, though by Sunday, much of the state will be in the 70s, said weather service meteorologist Jeff Kitsmiller.
Great Falls was heading toward a record high of 104F (40C), which would top its previous record of 101F (38C), while Helena was expected to match or surpass its record of 102F (39C), he said.
Still, it’s not as bad as the heat wave in mid-July, when some areas broke all-time records, including Billings, which reached 111F (44C) on July 12, Kitsmiller said.
“That was a rare heat wave,” he said. “This one fits for this time of year.”
The Montana Rescue Mission, a homeless shelter in Billings, opened its doors earlier than usual on Saturday to provide relief from temperatures that could reach 106F (41C). Dozens of people were expected throughout the day, and the shelter planned to provide dinner, beds and breakfast, a receptionist said.
Great Falls Parks and Recreation's four swimming pools and three splash pads were crowded with people trying to beat the heat, said Katy Houseman, who works at one of the city's recreation centers.
“They’re definitely hitting the pools and doing the splash pads outside and then trying to hide inside where there’s air conditioning,” said Houseman. “It's super, super hot today.”
Forecasters were warning that this heat wave, combined with drying from past heat, will add to wildfire risks across the West.
“We’re definitely worried about that” in Montana, where fires already are burning and high winds are forecast for the weekend, said Kitsmiller, adding that most of the state was under a red flag warning.
In Nevada, “with this heat dome setting up, we’ve lost some of the moisture that we did have — like relative humidity in the afternoon bottoming out in the single digits in quite a few places,” Stessman said.
The U.S. Forest Service has said there is an enhanced wildfire risk through Sunday in most of Southern California except for the coastline.
Extreme heat and drought also have created dangerous wildfire conditions in the Pacific Northwest.
Washington Gov. Bob Ferguson declared a state of emergency Saturday after unusually high temperatures and high winds exacerbated record wildfires across the state. He also banned most outdoor and agricultural burning through the end of September.
Ferguson’s proclamation went into effect ahead of an unprecedented “particularly dangerous situation” Red Flag Alert by the National Weather Service, which rated the weather risk as “extreme” across Eastern Washington. More than 312 square miles (808 square kilometers) are currently burning in 12 large fires.
A red flag alert also was given for eastern Oregon, where crews are battling several large wildfires, including the Rowe Creek Complex fire, which has grown to 490 square miles (1,269 square kilometers) with 57% containment.
Climate change from the burning of coal, oil and natural gas is causing larger, more intense and longer-lasting heat waves — which lead to more intense droughts and contribute to larger, more destructive wildfires.
This year’s weather is also expected to be affected by El Nino, a natural warming of the equatorial Pacific that alters weather patterns and spikes temperatures across the globe.
The current El Nino is expected to rank as among the most intense since the weather service began tracking the phenomenon in 1950, experts said. It's already broken records for intensity at its early stages, United Nations officials warned Friday.
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Associated Press writer Martha Bellisle in Seattle contributed to this report.
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