(The Center Square) – With extreme heat expected to hit California and the West through Labor Day Weekend, California grid operators are calling on residents to voluntarily conserve electricity by avoiding the use of large electronics and even stop charging electric vehicles.

The California Independent System Operator issued a statewide Flex Alert Wednesday, calling on residents to voluntarily conserve energy between 4:00 and 9:00 p.m. to reduce stress on the electrical grid.

The announcement comes days after California air regulators announced that the state will phase out the sale of gas-powered vehicles by 2035, mandating that all new cars sold in the state by 2035 must be zero-emission vehicles or hybrids.

In a notice posted Wednesday, Cal ISO urged residents to set thermostats at 78 degrees, avoid the use of larger electronics, turn off unnecessary lights and avoid charging electric vehicles.

“Reducing energy use during a Flex Alert can help stabilize the power grid during tight supply conditions and prevent further emergency measures, including rotating power outages,” the announcement said. 

The alert is the first of what could be several Flex Alerts issued throughout the holiday weekend. Cal ISO issued a warning Tuesday afternoon that it could issue a “series of emergency notifications” preparing the public for potential energy shortages if grid and weather conditions worsen.

“The power grid operator expects to call on Californians for voluntary energy conservation via Flex Alerts over the long weekend,” Tuesday’s announcement said.

A heat wave is expected to hit the state over the holiday weekend, with temperatures expected to be 10-20 degrees above normal in Northern California and 10-18 degrees higher in Southern California, Cal ISO said. 

Cal ISO’s recommendation to unplug electric vehicles was met with criticism from energy groups like Power the Future, which drew the connection between the EV mandate and Wednesday's Flex Alert.

“When it comes to good energy policy, California’s leaders are unplugged from reality,” Daniel Turner, founder and executive director for Power The Future, said in a statement. “Temperatures are soaring, and residents are being asked to power down their everyday appliances and air conditioners over a long holiday weekend.”

To prepare for a Flex Alert, the grid operator recommends pre-cooling the home to 72 degrees and using major appliances like dishwashers before 4:00 p.m.