Western US heat dome pushes temperatures near records, heightens wildfire risk

A heat dome sent temperatures near record highs across the western United States on Saturday. The intense spell strained cooling centres and sharply raised wildfire danger in dry, windy areas.

In Short

• Las Vegas and Phoenix faced brutal daytime heat with no overnight relief
• Cooling centres in Phoenix and shelters in Montana saw steady demand
• Great Falls and Helena approached or exceeded previous August temperature records

A heat wave gripped large parts of the western United States on Saturday, with temperatures hovering near record highs, raising wildfire risks in areas that are already dry or burning and prompting warnings for people to stay indoors. Forecasters said a ridge of high pressure, known as a heat dome, was trapping heat close to the ground from Arizona to Montana.

National Weather Service meteorologists said the spell of heat would be relatively short-lived, but dangerous conditions were expected across the region through the weekend. Las Vegas was forecast to reach 115F (46C), Phoenix 116F (47C), El Centro in California a record 118F (48C), and Great Falls in Montana a record 104F (40C).

In Las Vegas, Saturday's forecast high was 10 degrees above normal, and dangerous heat was expected to continue through Sunday, when the high was forecast at 114F, weather service meteorologist Morgan Stessman said. Overnight lows in the upper 80s to low 90s were expected to make conditions especially dangerous because they would not allow people's bodies to recover. "There's just no relief overnight," Stessman said.

People were urged to stay indoors and keep hydrated. At the Justa Center in Phoenix, which serves seniors but opens to the public as a cooling centre in the afternoon, operations director Rudy Soliz said the biggest challenge was keeping up with the need for water and electrolytes. He said about 200 people come in every day. "Anybody can come in, get a meal, sign up, get checked in through the cooling centre, sit down, relax, watch a little TV, you know, catch themselves before they move on to another cooling centre or their destination," he said.

Several cities were nearing record temperatures. Stessman said the August record for Las Vegas is 116F (47C), while the hottest temperature ever recorded there was 120F (49C) in July 2024, which was also the hottest summer on record. In Montana, the entire eastern side of the state was under an extreme heat warning on Saturday, though much of the state was expected to be in the 70s by Sunday, weather service meteorologist Jeff Kitsmiller said.

Kitsmiller said Great Falls was heading towards a record high of 104F (40C), above its previous record of 101F (38C), while Helena was expected to match or surpass its record of 102F (39C). He said it was still not as severe as the mid-July heat wave, when some places broke all-time records, including Billings, which reached 111F (44C) on July 12. "That was a rare heat wave," he said. "This one fits for this time of year."

In Billings, the Montana Rescue Mission, a homeless shelter, opened earlier than usual on Saturday to offer relief from temperatures that could reach 106F (41C). A receptionist said dozens of people were expected through the day, and the shelter planned to provide dinner, beds and breakfast. In Great Falls, Parks and Recreation's four swimming pools and three splash pads were crowded as people tried to cope with the heat, said Katy Houseman, who works at one of the city's recreation centres. "They're definitely hitting the pools and doing the splash pads outside and then trying to hide inside where there's air conditioning," Houseman said. "It's super, super hot today."

Forecasters said the heat wave, along with drying caused by earlier heat, was increasing wildfire risks across the West. "We're definitely worried about that" in Montana, where fires were already burning and high winds were forecast for the weekend, Kitsmiller said, adding that most of the state was under a red flag warning. In Nevada, Stessman said, "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."

The US Forest Service said there was an enhanced wildfire risk through Sunday across most of Southern California apart from the coastline. Extreme heat and drought have also created dangerous wildfire conditions in the Pacific Northwest. Washington Governor Bob Ferguson declared a state of emergency on Saturday after unusually high temperatures and strong winds worsened record wildfires across the state. He also banned most outdoor and agricultural burning until the end of September.

Ferguson's proclamation took effect ahead of what the National Weather Service described as an unprecedented and "particularly dangerous situation" Red Flag Alert, with the weather risk rated "extreme" across eastern Washington. More than 808 square kilometres are currently burning in 12 large fires. A red flag alert was also issued for eastern Oregon, where crews are fighting several large wildfires, including the Rowe Creek Complex fire, which has grown to 1,269 square kilometres and is 57 per cent contained.

The article said climate change caused by the burning of coal, oil and natural gas is leading to larger, more intense and longer-lasting heat waves, which in turn bring more severe droughts and contribute to bigger and more destructive wildfires. It added that 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 raises temperatures globally. Experts said the current El Nino is expected to rank among the most intense since tracking began in 1950, and United Nations officials warned on Friday that it had already broken early-stage records for intensity.

Overall, the western United States remained under dangerous heat on Saturday, with several cities close to record temperatures, cooling centres and shelters trying to meet rising demand, and wildfire concerns growing across dry and windy parts of the region.

With PTI Inputs

- Ends