California flex alert extended for second day amid hot weather

A bright red sun sets
High temperatures across California prompted electrical system regulators to extend a statewide flex alert into Thursday.
(Gary Robbins / The San Diego Union-Tribune)

California electrical system regulators are extending a statewide flex alert into Thursday as soaring temperatures across the region are expected to create high power demand.

The flex alert will run from 4 p.m. to 9 p.m. Thursday, the California Independent System Operator said.

“The ISO is predicting an increase in electricity demand, primarily from air conditioning use,” said the nonprofit group, which manages the flow of electricity on high-voltage power lines and operates the state’s wholesale energy market.


That extra demand can stretch supplies thin and strain the power grid, the group said.

“Consumers are urged to conserve electricity, especially during the late afternoon and early evening, when the grid is most stressed due to higher demand and solar energy production falling,” the group said.

Decreasing energy use during a flex alert can stabilize the grid and help prevent emergency measures like rolling blackouts, Cal ISO said.

Temperatures are expected to be 5 to 10 degrees above normal in Southern California and 3 to 10 degrees above normal in inland Northern California through the weekend, the energy regulator said.

Although inland regions will see the highest temperatures, coastal areas could see some warming as well, the group said.

“Widespread heat waves affecting other western states limits the California ISO’s ability to import energy from neighboring power grids,” the group said.


What to do during a flex alert

  • Adjust your thermostat to 78 degrees or higher during the alert hours, unless medically necessary. Turn it off if you will not be home.
  • Use a fan instead of air conditioning when possible.
  • Draw drapes and turn off unnecessary lighting.
  • Keep the main refrigerator full (with bottles of water if nothing else) and unplug additional refrigerators.
  • Avoid using electrical appliances and devices. Put off tasks such as vacuuming, laundry, running the dishwasher and computer time until after 9 p.m., or do them earlier in the day.
  • Set your pool pump to run overnight instead of during the day.
  • Pre-cool your home by lowering the thermostat before a flex alert begins.
  • Remember that saving water saves energy.
  • Find more tips at

Staff writer Hayley Smith contributed to this report.