State of emergency declared over California heatwave as 50m people placed under alerts

Temperatures are forecast to reach well above 100F (38C) in much of California on Thursday, and up to 113F (45C) in the Coachella Valley

A dangerous heatwave is descending in the US west with parts of California expected to reach up to 115 degrees Fahrenheit (46 degrees Celsius) through the Labor Day weekend.

More than 50 million people are under heat advisories, watches and warnings, as scorching temperatures spread across California and Nevada, as well as parts of Arizona, Oregon and Idaho.

Temperatures are forecast to reach well above 100F (38C) in much of California on Thursday, and up to 113F (45C) in the Coachella Valley, 111F (44C) in the San Fernando Valley and 102-107F (39-42C) across the Central Valley from Bakersfield to Redding.

But by Monday and Tuesday, temperatures will have pushed even higher, soaring to 107-111F (42-44C) in the Central Valley, and over 100F (38C) in much of inland Los Angeles and Riverside counties.

California Governor Gavin Newsom declared a state of emergency on Wednesday in response to the heatwave. The state power grid operator has warned of potential blackouts as energy demands ramp up, in large part from air conditioning.

Residents should avoid using major appliances, set their thermostats higher and avoid charging electric vehicles during the late afternoon and early evening when the grid is under the most stress, according to grid operator California ISO.

Governor Newsom’s emergency declaration includes provisions to temporarily boost energy production as the heatwave kicks in.

“This is just the latest reminder of how real the climate crisis is, and how it is impacting the everyday lives of Californians,” he said in a statement.

“While we are taking steps to get us through the immediate crisis, this reinforces the need for urgent action to end our dependence on fossil fuels that are destroying our climate and making these heat waves hotter and more common.”

The severe temperatures increase the risk of heat-related illnesses. Heat stroke, when the body can’t cool itself down, can be extremely serious and even fatal.

The temperatures in California have record-breaking potential. Some areas around Los Angeles broke the 31st August temperature record on Wednesday, according to The Los Angeles Times.

The Los Angeles Times also reported that many schools are facing serious heat threats, as outdoor areas often lack shade or green space, putting kids directly into the sun when they go for recess. Asphalt around schools has reached up to 145F (63C), the paper reports, and some parents are demanding that the school district builds new green space and set up shaded areas.

Phoenix, Arizona and Las Vegas, Nevada and their surrounding areas are also supposed to reach well above 100F (38C) through the weekend. Temperatures in eastern Oregon and Washington, as well as parts of Idaho, are forecast to hit up to 105F (41C) on Friday, and temperatures in eastern Montana will reach around 100F (38C) on Saturday.

In some places, temperatures will exceed normal ranges. San Francisco, for instance, will see highs of around 82F (28C) this weekend. Normally, high temperatures in September are around 70F (21C).

The heatwave is caused by a “heat dome”, a mass of high-pressure air that can trap heat over a region for days on end.

The National Weather Service has warned that this kind of heat can be incredibly dangerous, and encouraged people to stay hydrated, find air conditioning and check in on people who may be more vulnerable to extreme heat like the elderly and those with pre-existing health conditions.

Cooling centres have been opened across California to help people find air conditioning.

High temperatures combined with dried-out landscapes across California due to the prolonged drought are raising the wildfire risk.

Two fires broke out in southern California on Wednesday, one in northern Los Angeles County and one along the US-Mexico border outside of San Diego.

Both blazes spread quickly overnight and spurred mandatory evacuations. At least eight firefighters were injured battling the LA county blaze, which shut down part of a major route, 5 Freeway.

Other fires are burning in Yosemite National Park, along the Sierra Nevada mountains, and near the border with Oregon.

The Rum Creek Fire, near Grant’s Pass, has burned through nearly 15,000 acres, roughly one-third the size of Washington, DC, and remains largely uncontained.

Extreme heatwaves are expected to worsen as the global average temperature rises due to the climate crisis. According to the United Nations leading climate science panel, heatwaves that once occurred once every 10 years would happen every other year if the world hit 2C of warming above 19th-century temperatures. Already, the world has warmed about 1.1-1.2C.