California ISO issues Flex Alert for today, Aug. 31

FOLSOM, Calif. – The California Independent System Operator (ISO) has issued a statewide Flex Alert, a call for voluntary electricity conservation, for today, Aug. 31 from 4 p.m. to 9 p.m., due to high temperatures pushing up energy demand and tightening available power supplies. 

With excessive heat in the forecast across much of the state and Western U.S., the grid operator is expecting high electricity demand, primarily from air conditioning use, and is calling for voluntary conservation steps to help balance supply and demand. 

Additional Flex Alerts are also possible through the Labor Day weekend as record setting temperatures are forecast across much of the West. 

In what’s likely to be the most extensive heat wave so far in the West this year, temperatures in Northern California are expected to be 10-20 degrees warmer than normal through Tuesday, Sept. 6. In Southern California, temperatures are expected to be 10-18 degrees warmer than normal. Death Valley is currently forecast to peak at 126 degrees on Saturday, which would tie the highest temperature ever recorded on Earth in the month of September. 

Today’s Flex Alert is scheduled between 4 p.m. and 9 p.m., when the grid is most stressed from higher demand and less solar energy. During that time, consumers are urged to conserve power by setting thermostats to 78 degrees or higher, if health permits, avoiding use of major appliances and turning off unnecessary lights. They should also avoid charging electric vehicles while the Flex Alert is in effect. 

To minimize discomfort and help with grid stability, consumers are also encouraged to pre-cool their homes and use major appliances and charge electric vehicles and electronic devices before 4 p.m., when conservation begins to become most critical. 

Flex Alert Conservation Actions Before 4 p.m.:

  • Pre-cool home by setting the thermostat to as low as 72 degrees  
  • Use major appliances, including: Washer and dryer, dishwasher, oven and stove for pre-cooking and preparing meals  
  • Charge electric vehicles
  • Adjust blinds and drapes to cover windows 

From 4 p.m. to 9 p.m.:

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

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. 

For information on Flex Alerts, and to find more electricity conservation tips, visit