Flex Alert issued for Wednesday due to heat and tight power supply

September 07, 2021


California-ISO

Consumers urged to reduce energy use from 4-9 p.m. to protect grid reliability

FOLSOM, Calif. – The California Independent System Operator (ISO) has issued a statewide Flex Alert calling for voluntary electricity conservation Wednesday, Sept. 8, from 4 p.m. to 9 p.m., due to predicted high energy demand and tight supplies on the power grid.

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 increased demand can make electricity supplies tight and strain the power grid, making conservation essential.

During the Flex Alert time period, consumers are asked to lower their thermostats to 78 degrees or higher, if health permits, and take other voluntary measures that include avoiding the use of major appliances and unnecessary lights.

To take full advantage of all available supply, the ISO has also issued a restricted maintenance operation (RMO) for tomorrow from noon to 9 p.m., notifying ISO participants to avoid taking grid assets offline for routine maintenance until the RMO is lifted.

Conserving electricity during the late afternoon and early evening is crucial because that is when the grid is most stressed due to higher demand and declining solar energy production.

In the past, reducing energy use during a Flex Alert has helped operators keep the power grid stable during tight supply conditions and prevented further emergency measures, including rotating power outages.

For information on Flex Alerts, and to get more electricity conservation tips, visit FlexAlert.org.

Tips before a Flex Alert:

  • Pre-cool home by setting the thermostat to as low as 72 degrees
  • Use major appliances:
    • Washer and dryer
    • Dishwasher
    • Oven and stove for pre-cooking and preparing meals
  • Adjust blinds and drapes to cover windows

Tips during a Flex Alert from 4 p.m. to 9 p.m.:

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

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.

Follow developing grid conditions at the ISO’s News webpage, under the System Conditions Bulletin, or follow us on Twitter at @California_ISO.

Click here to learn more about System Alerts, Warnings and Emergencies. Follow grid conditions in real time at ISO’s Today’s Outlook, or download the free ISO Today mobile app.

Sign up for
Flex Alerts

Monitor grid conditions on Today's Outlook

Download 
ISO Today app

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. Glossary of terms and acronyms

Click here to learn more about System Alerts, Warnings and Emergencies. Follow grid conditions in real time at ISO’s Today’s Outlook, or download the free ISO Today mobile app.

This advisory is based on the best data available at the time of its release. Grid conditions can change rapidly and are subject to change without warning. This forecast is accepted by the recipient on the condition that errors, omissions and/or changes to the contents shall not be made the basis for any claim, demand or cause of action against the California ISO.