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A statewide Flex Alert has been issued for Wednesday as above-normal temperatures and high energy demand threaten California’s electric grid.

The alert will be in place from 4 p.m. to 9 p.m. Wednesday in an attempt to avoid power disruptions and rolling blackouts, the California Independent System Operator, which runs most of the state’s electric grid, said in a news release Tuesday.

“With above-normal temperatures in the forecast for much of California and the West, the power grid operator is predicting an increase in electricity demand, primarily from air conditioning use,” the ISO said.

Very warm to hot weather is expected to persist across Southern California throughout the week, according to the National Weather Service. “Dangerously hot conditions” are expected in the Antelope Valley through Wednesday, the NWS said, and a heat advisory is in place there through Thursday.

A heat advisory is also in place in the eastern San Fernando Valley from Thursday through Saturday, the Los Angeles County Public Health Department said. And, a heat alert will be in place for the western San Fernando Valley and eastern San Gabriel Valley on Friday.

Elevated fire weather conditions are also in place, the NWS said.

Flex Alerts are a call to consumers to voluntarily conserve energy when demand for power could outstrip supply, which generally occurs during heat waves when electrical demand is high. Such conservation would help ease the strain on the grid during the crucial evening hours when solar energy is diminished or no longer available, the ISO said.

To take “full advantage of all available supply,” the ISO has also issued a restricted maintenance operation for noon to 9 p.m. Wednesday.

Before the Flex Alert takes effect Wednesday and when solar energy is abundant, residents are encouraged to take these steps to be comfortable and help grid operators balance supply and demand:

  • Pre-cool your home by lowering the thermostat to 72 degrees
  • If you need to use your major appliances, do it before the Flex Alert is in effect, when solar energy is plentiful
  • Close blinds and drapes to keep the heat out of your home or apartment
  • Charge electronic devices and electric vehicles so there’s no need to do it later

During the Flex Alert period, consumers are encouraged to:

  • Set thermostats to 78 degrees or higher, or use fans to cool the home, if your health permits
  • Avoid using major appliances like dishwashers, clothes washers and dryers
  • Turn off all unnecessary lights
  • Unplug unused items

Rolling blackouts have become a method for utility companies in the state to intentionally turn off the power when it gets too windy in dry summer months to prevent power lines from toppling and starting wildfires. Such blackouts in August 2020 were the first in nearly two decades caused by an energy shortage.