What you need to do during California’s Flex Alert power emergency

A street barber cuts a man's hair on the sidewalk.
Jacket Rashad, a street barber, gives Karim Mejia Mawema, a food vendor, a haircut on Degnan Boulevard in Leimert Park on June 15.
(Jason Armond / Los Angeles Times)

Amid a blistering heat wave, the California Independent System Operator, which monitors power lines across the state, issued a Flex Alert from 5 to 10 p.m. Thursday and again on Friday to encourage reduced energy use because of the strain on the state’s grid.

Residents are advised to avoid lowering the thermostat during those hours and to complete tasks involving high amounts of energy beforehand, such as using major appliances and charging devices and electric cars.

“The public’s help is essential when extreme weather or other factors beyond our control put undue stress on the electric grid,” Elliot Mainzer, president and chief executive officer of the ISO, said in a statement. “We have seen the huge impact that occurs when consumers pitch in and limit their energy use. Their cooperation can really make a difference.”

Officials hope voluntary power reductions can avoid the types of problems with the grid that led to power shutoffs in some areas during last year’s heat waves. In August, the ISO declared a statewide Stage 3 emergency for the first time since 2001 because of excessive heat driving up electricity use, and the agency ordered utilities to implement power disruption programs.


After record-high heat the previous day, Southern California was again reaching blistering temperatures on Wednesday.

June 16, 2021

Here the basic points about power conservation from Cal ISO:

When is this alert in effect?

The Flex Alert runs from 5 to 10 p.m. Thursday, then again during the same hours Friday.

What is a Flex Alert?

A Flex Alert is a call to consumers to voluntarily cut back on electricity and shift electricity use to off-peak hours (normally after 9 p.m.).

As part of an educational and emergency alert program, Flex Alerts inform consumers about how and when to conserve electricity. The effort is critical to achieving high levels of conservation during heat waves and other challenging grid conditions, including wildfires or when major power plant or power lines are unavailable.

What do you do if you hear that a Flex Alert has been called?

  • The key hours on hot days are usually between 4 and 9 p.m. during the “air conditioning rush hour.” This week’s alerts will take place from 5 to 10 p.m. “due to operational needs,” the agency said.
  • 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 dinner (9 p.m.) or do so earlier in the day.
  • Set your pool pump to run overnight instead of during the day.
  • Saving water saves energy.
  • Pre-cool your home by lowering the thermostat.
  • Find more tips at