Californians were today told not to charge their electric vehicles as the aging electricity grid struggles with a fearsome heatwave.
The move comes just days after the state said it would stop selling petrol and diesel-powered cars,
Temperatures as high as 112F (44C) were expected in some Los Angeles suburbs as a huge heat dome bakes a swathe of the western United States.
The sweltering weather is expected to put huge demands on the already-stretched power grid, especially when people crank up the air conditioners during the broiling hours after work and school.
"Consumers are urged to reduce energy use from 4pm to 9pm when the system is most stressed because demand for electricity remains high and there is less solar energy available," said the American Public Power Association, a body that represents public utilities.
"The top three conservation actions are to set thermostats to 78 degrees or higher, avoid using large appliances and charging electric vehicles, and turn off unnecessary lights."
California's power companies routinely call for households to limit their usage during the so-called "shoulder hours", when rooftop solar panels stop producing electricity but demand remains high because of still-elevated temperatures.
The call to limit electric vehicle charging comes a week after state regulators banned the sale of new petrol and diesel-powered vehicles from 2035.
All but a handful of SUVs, cars and light trucks will have to produce zero tailpipe emissions, with only highly efficient plug-in hybrids permitted to burn fossil fuels.
The move was hailed as a game-changer for the EV industry because of the size of California's car market and the potential it has to set national, and even international, standards.
'Dangerously hot'
The call to conserve power was greeted with derision on Twitter, where some said it was proof the state had not thought through its green agenda.
The National Weather Service has issued an "excessive heat warning" for most of California, as well as parts of Arizona and Nevada.
"Dangerously hot conditions expected ... until Sunday evening," the NWS said.
Dangerous heat is ongoing and expected to continue into the weekend across the western U.S.
— National Weather Service (@NWS) August 31, 2022
Knowing the signs of heat illness can be a matter of life or death,https://t.co/asAP0ZR0oK pic.twitter.com/eU3VjJRX2E
"A prolonged period of excessive heat will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities.
"Those without access to adequate or reliable cooling or hydration will be at most risk, but much of the population could be susceptible to impacts as well."
Nighttime temperatures are not expected to offer much relief, with lows struggling to get below 80F (26.7C) in many places.
It is not unusual for southern California to experience heat waves in September, but temperatures above 100F (37.8C) are considered hot even for a place almost perpetually baked by sunshine.
The heatwave comes after swathes of the southwest were lashed with torrential rains over recent weeks.
Some areas, including the notoriously dusty Death Valley, suffered flooding, and one person died after being swept away in Zion National Park in Utah.
Scientists say global warming, which is being driven chiefly by humanity's use of fossil fuels, is making natural weather variations more extreme.
Heatwaves are getting hotter and more intense, while storms are getting wetter and, in many cases, more dangerous.
