A brutal, potentially record-breaking heatwave is setting over the US west, the latest in a string of extreme temperature events that’s putting communities on high alert for heat-related illness and death.
More than 50 million Americans live in areas now under excessive heat watches, warnings and advisories. Temperatures are expected to hit 115F (46C) in the coming days across parts of southern California, Sacramento and the San Joaquin Valley, according to the National Weather Service. In Death Valley, temperatures were forecast to reach more than 120F (49C) – and perhaps match the highest temperature observed globally in the month of September.
Extreme heat warnings have been triggered up and down the state, including in the Bay Area. Temperatures are expected to build throughout the week, with northern and southern California bracing for the highest temperatures during the long weekend.
Parts of the Pacific north-west, Nevada, Idaho and Montana will also face dangerous temperatures. Boise, Idaho, is expected to finish August with an average temperature of 80F (27C) – the highest since record keeping began in 1875. Temperatures are expected to be eight to 12 degrees above normal in north-west Arizona, south-east California and southern Nevada.
Across many of these areas, temperatures are expected to cool only slightly overnight – elevating the risk for heatstroke and deaths, especially for vulnerable populations who lack air conditioning.
The extreme temperatures are a result of a “heat dome” bearing over the region – a ridge of high atmospheric pressure that acts as a lid, trapping in heat. Although climate crisis doesn’t cause heat domes, scientists expect it to drive more extreme weather.
The heatwave is just the latest of several to hit the US this summer. As they grow more frequent and intense, California has debated naming and ranking them – similarly to hurricanes – to underscore their significance. Extreme heat kills more people in the US than any other weather event, according to the National Weather Service. In interior northern California, the service has warned that “the entire population is at risk” of deadly heat.
California officials have warned that the heat could strain the state’s energy resources as demand for air conditioners and other appliances surge. The strain could be especially acute in a year that has already seen hydropower disrupted due to drought. With the heat wave just beginning, officials have called for residents to conserve energy where possible to avoid outages, describing the coming days as “the most extensive heat wave in the west so far this year” in a news release.
Additional “FlexAlerts,” a warning to conserve energy “are also possible through the Labor Day weekend as record setting temperatures are forecast across much of the west”, the state’s grid operator said.
High temperatures are also expected to accelerate the formation of ground-level ozone, or smog, which exacerbates respiratory issues. In southern California, officials have issued an ozone advisory due to the heatwave, advising people to stay indoors and avoid physical exertion.
Officials also warn that the high temperatures could further prime the parched, drought-addled west for wildfires. Parts of the west have already seen an explosive spring and summer, with major fires in the south-west and Alaska.
On Sunday, Oregon governor, Kate Brown, declared a state of emergency due to the “imminent” threat of wildfire. “It is imperative that we act now to prevent further loss – of life, property, business, and our natural resources,” she said.
In California, which has seen a relatively quiet fire season compared with recent years, officials advise that the heat will not only further dry and prime the landscape for explosive fire, but also increase the risk of ignitions. “With the warming and drying trend this week and over the weekend, we will see very dangerous heat risk and increased fire weather concerns over portions of interior northern California,” advised the National Weather Service in Sacramento.
The National Interagency Fire Center has warned of high fire risk in much of northern California, due to “warm temps, gusty winds”, low humidity, and “flammable fuels”.
