Statewide Flex Alert Issued Today Due to Heat, Tight Supply


The California Independent System Operator (ISO) has issued a statewide Flex Alert, a call for voluntary electricity conservation, for today from 4-9 p.m., due to high energy demand and tight supplies across the West.

With higher than normal temperatures in the forecast for parts of interior Northern California, the power grid operator is predicting an increase in electricity demand, primarily from air conditioning use. The increase can make electricity supplies tight and cause strain on the state’s power grid.

Temperatures are expected to soar above 100 degrees in the Valley through Friday. In Southern California, drier and warmer conditions can be expected through Thursday as high pressure aloft strengthens. On Friday and Saturday, some monsoonal moisture may move into the area. In the Bay Area, a brief warming trend will begin Wednesday through Friday across the interior as high pressure dominates much of the western states, though onshore flow and a continued marine influence will keep the coast generally seasonable.

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. Turning off unnecessary lights, delaying the use of major appliances until after 9 p.m., and setting the air conditioner thermostats to 78 degrees or higher, if health permits, are also recommended.

A Flex Alert is issued by the ISO when the electricity grid is under stress because of generation or transmission outages, or from persistent hot temperatures.

Conservation Tips

Tips before a Flex Alert: 

  • Pre-cool home by setting the thermostat to as low as 72 degrees
  • Use major appliances:
    • washer and dryer – do laundry
    • oven and stove – pre-cook and prep meals
    • run the dishwasher
  • Adjust blinds and drapes to cover windows

Tips during a Flex Alert (4-9 p.m.):

  • Set thermostat to 78 degrees or higher, if health permits
  • Avoid using major appliances
  • Turn off all unnecessary lights

The conservation measures can help stabilize the power grid during a time of tight demand and supply, and avoid power interruptions. Reduced electricity use during a Flex Alert can prevent further emergency measures, including rotating power outages.

For more information on Flex Alerts, and to get more electricity conservation tips, visit Follow developing grid conditions at the ISO’s news webpage, under the System Conditions Bulletin, or follow on Twitter @California_ISO.

Additional heat safety tips can be found on the Cal OES Summer Heat Resources page.