Arizona, California, Nevada… Heatwave Spreads Across the Western United States

As California braces for an extreme heat wave this weekend, the city of Phoenix in neighboring Arizona is experiencing a scorching summer.

It’s certainly always particularly hot at this time of year in the central part of the state, but summer seems endless this year: Phoenix, for example, had its 100th consecutive day on Tuesday, September 3, since May 27, with temperatures of at least 100°F (degrees Fahrenheit), or 37.8°C.

The record of 76 days in a row, which was set in 1993, has been largely broken according to data from the American National Weather Service (NWS). And no respite is expected in the coming days while, according to NWS meteorologists, long periods of heat in the desert are usually interrupted by rain at this time of year.

Phoenix residents have experienced 37 nights this summer where the temperature did not drop below 90.2 degrees Fahrenheit, another record. “Not being able to cool down at night can affect people’s health because heat can build up in the body”Erinanne Saffell, a climatologist at Arizona State University, told AP.

Many dead

Public health officials in Maricopa County, where Phoenix is ​​located, said that as of Aug. 24, 150 heat-related deaths had been confirmed so far this year, with another 443 under investigation. In 2023, there have been 645 heat-related deaths in the county of about 4.5 million people.

Across the western United States—from Arizona to California to Nevada to Utah to New Mexico—the summer of 2024 is on track to shatter heat records. In Clark County, Nevada, which includes Las Vegas, 181 heat-related deaths have been confirmed so far this year. But the death toll is likely much higher, officials say, because most cases take three months to complete.

Death Valley, California, one of the hottest places on Earth, is expected to see temperatures reach 47 degrees Celsius, slightly below the 50 degrees Celsius already reached in July in the desert region.

Closer to the Pacific Ocean, in some areas of Los Angeles, the second largest city in the United States, a peak of 45°C is expected, as in Woodland Hills, an upscale neighborhood located inland about fifteen kilometers from Malibu, located on the coast.

Increase in the frequency of heat waves

According to meteorologists, a high pressure system is expected to push temperatures well above seasonal norms in this region, with differences of more than 10 degrees Celsius in some cases. The heat wave is expected to extend from Wednesday noon to Friday evening, the US weather service warned. Los Angeles Mayor Karen Bass announced the opening of several air-conditioned shelters so that city residents without access to air conditioning can take refuge there.

Even coastal areas, which have enjoyed a milder summer as usual, will this time experience the same temperatures as those endured inland, according to climatologist Daniel Swain.

“Most areas very close to the coast had escaped temperature records this summer”which means that “Although a majority of California’s land area experienced a record-breaking summer in terms of temperature, that was not the case for the majority of its population.”the coasts being the most populated areas, he writes on his blog.

Repeated heat waves are a marker of climate change caused by humanity’s reliance on fossil fuels, scientists say. According to a recent report by the US Environmental Protection Agency that analyzed data from 50 major US cities, the average frequency of heat waves there has increased from two per year in the 1960s to six per year in the 2010s and 2020s.