A dangerous heat wave will bring record-breaking temperatures to parts of the Western U.S. this weekend, 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.
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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 is 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 are 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, said weather service meteorologist Jeff Kitsmiller.
Great Falls was expected to reach 104F (40C), topping 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.”
By Sunday, much of the state will have highs in the 70s, he said.
Forecasters are 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.
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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