A large wave of extreme heat has engulfed much of the western United States, where temperatures have approached record levels, the Associated Press reports.

The heat is increasing the danger of new wildfires in areas already suffering from drought and active blazes, meteorologists said.

According to the U.S. National Weather Service, the cause of the abnormal heat is a so-called “heat dome” — an area of high pressure that traps hot air near the ground. It has spread from Arizona to Montana.

Forecasters note that the heat will be relatively short-lived, but dangerous conditions will persist in the coming days.

In Las Vegas, the temperature rose to 46 degrees Celsius on Saturday — the hottest day of the year and just one degree below the daily record. In Phoenix, temperatures were expected to reach 47 degrees, while in El Centro, California, forecasters predicted a record 48 degrees. Even in Montana, temperatures could reach 40 degrees — in the city of Great Falls, a new high for this period was expected.

Meteorologists warned that nighttime temperatures are especially dangerous: in some areas they do not fall below 31–33 degrees, preventing the body from recovering from the daytime heat.

Residents of the affected regions are advised to stay indoors whenever possible, drink more water, and avoid prolonged time outside. Cooling centers are opening in cities. In Phoenix, for example, one such center receives about 200 people ежедневно, providing visitors with water, food, and a place to stay in a cool room.

The heat is also significantly increasing the risk of wildfires. In Montana, where fires are already burning, authorities warned of danger due to the combination of high temperatures, dryness, and strong winds. Most of the state is under a fire weather warning.

In Nevada, the “heat dome” has reduced air humidity — in some areas it drops to single digits during the day, creating favorable conditions for the spread of fire.

In Southern California, the U.S. Forest Service declared an elevated fire risk, except in coastal areas. In Washington state, Governor Bob Ferguson declared a state of emergency after abnormal heat and strong winds worsened the wildfire situation. Twelve large fires are burning in the region, covering a total area of more than 800 square kilometers.

Eastern Washington received a “particularly dangerous situation” warning from the National Weather Service because of the extreme fire threat. The state has also imposed a ban on most types of open and agricultural burning until the end of September.

Fire danger also remains in Oregon, where firefighters are battling several large blazes. The Rowe Creek Complex fire has grown to about 1,270 square kilometers, although rescuers have managed to contain more than half of its area.

Scientists link the increasing frequency and intensity of such heat waves to climate change caused by emissions from burning coal, oil, and gas. Warming contributes to longer periods of extreme heat, worsening droughts, and creating conditions for larger wildfires.

An additional factor this year may be the natural phenomenon El Niño — the warming of waters in the equatorial Pacific Ocean, which affects global weather patterns and contributes to higher temperatures. According to experts, the current El Niño could become one of the strongest since records began in 1950.