An unusually intense heat dome will incinerate much of the western United States this weekend, bringing tens of millions of temperatures from California to Canada, the hottest so far this year.
Dozens of record high temperatures are expected to fall in at least 12 Western states over the weekend, with about 50 million people under heat warnings.
🥵 Get heat forecasts with the CNN Weather app
From Friday into Tuesday, high temperatures will be nearly 10 to 20 degrees warmer than normal from Southern California to the northern Rocky Mountains and Plains regions, even at the peak of summer. Death Valley, California, is expected to experience a heatwave of 126 degrees, the highest temperature of the current heat wave.
This is the latest in a record-breaking heat wave that simultaneously hit the United States and Europe this summer. Studies show that human-induced climate change is making heatwaves like this one more likely to occur, more intense, and last longer. Particularly powerful and slow-moving thermal domes may also become more common as the world warms, but this is an area of active research.
The heat dome responsible for this heat wave could also set records for its intensity in parts of Southern California and Arizona. The heat dome acts like a pot lid, trapping and intensifying the hot air underneath. This is expected to reach even higher in the atmosphere than usual, meaning more air could be trapped underneath, potentially raising the upper limit of extreme surface temperatures.
Nearly 12 million people in the Southwest, Western Mountains, and northern Great Plains are at Level 4/4 “extreme” heat risk on Saturday and Sunday, and an additional 20 million people are at Level 3/4 “severe” heat risk. The National Weather Service warns that this level of heat will affect people who are unable to cool down and stay hydrated.
The weekend’s heat may be just the first wave of extreme temperatures from this heat dome, which will take hold for a long time, with more heat expected across much of the West starting Aug. 6.
By August 4, about 10% of the continental United States is expected to experience the hottest day of the year so far.
Billings, Montana, is expected to reach a high of 106 degrees on Saturday, setting an August record. The city hit an all-time high of 111 degrees just two weeks ago. After hitting a record high earlier this month, Salt Lake City will be nearing an August record with a predicted temperature of 104 on Saturday.
In California, people seeking relief on the coast should be careful, as highs are expected to reach 100 to 110 degrees across much of the state’s interior. Far offshore, Hurricane Genevieve will cause large waves and rip currents along the southern part of the state. Los Angeles County Fire Department lifeguards conducted nearly 2,000 sea rescues last week as millions of people visited the region’s beaches, the department said in a social media post.
Phoenix, Tucson, Arizona and Las Vegas are all expected to reach temperatures well above 110 degrees. In Maricopa County, home to Phoenix, 40 people have died from heatstroke so far this year, according to county data, and the summer heat still remains for several months.
According to National Weather Service statistics, heat is the deadliest extreme weather event in the United States, killing more people each year on average than tornadoes, hurricanes and lightning combined. According to the Japan Meteorological Bureau, emergency room visits due to heatstroke increase sharply on “severe” and “extreme” risk days.
Nighttime minimum temperatures will continue to be nearly 10 degrees higher than normal across the western region, and there will be little relief even after dark. This lack of cooling down is especially dangerous because it gives your body less time to recover before the fever rises again the next day.
The heat wave is also exacerbating wildfire and water concerns across the West, particularly in the arid Colorado River basin.
Much of the river basin, as well as the highlands of Central and Southern California, experienced below-average snowfall this winter. This heat makes the ground even drier, making the region more prone to wildfires.
Given the plight of river basins, other concerns center on water and energy supplies.
The combined water levels of Lake Mead and Lake Powell, the nation’s two largest reservoirs, are at historic lows and continue to fall.
These reservoirs, along with entire river basins, supply water to tens of millions of people. Heatwaves only exacerbate the rate of evaporation and decline in water levels from these vital resources.
