California ISO issues Flex Alert for today; takes other steps to reduce grid stress

July 9, 2021


Actions taken due to extreme heat and potential shortfall of power

FOLSOM, Calif. – With extreme heat forecasted across much of California into early next week, the ISO is using multiple tools, including a Flex Alert encouraging voluntary conservation, to maintain a safe and reliable grid.

In addition to the Flex Alert asking consumers to conserve between 4 p.m. and 9 p.m. today, July 9, the ISO has other steps it can take to reduce demand or access additional capacity to manage the grid and avoid potential shortages during evening hours when demand remains high, primarily from widespread air conditioning use.
On July 1, for example, the ISO solicited bids to secure additional capacity within California and the Western region. The grid operator is also working with business and industry to help them reduce energy use at critical times.

Voluntary conservation has helped keep the electric grid stable during past times of increased stress on the grid, including last month when high temperatures across the West strained the system with higher demand for power.

While the Flex Alert is in effect on Friday from 4 p.m. to 9 p.m., consumers are asked to:

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

To be as comfortable as possible during the Flex Alert hours, consumers are also strongly encouraged to take these steps earlier in the day:

  • Pre-cool your home by lowering the thermostat
  • Close window coverings to keep your home or apartment cool
  • If you need to use major appliances like your dishwasher, clothes washer and dryer, do so before the Flex Alert takes effect
  • Pre-charge electronic devices Close window coverings to keep your home or apartment cool
  • Pre-charge electric vehicles

For information on Flex Alerts, to get more electricity conservation tips, and to sign up for conservation alerts, visit the ISO's Flex Alert website. Visit the ISO's News page for more information on the heat wave's impacts on grid operations, and to learn more about alerts, warnings and emergency notices.

For updates on grid operations, follow us on Twitter at @California_ISO or @FlexAlert, or monitor system conditions in real time at ISO's Today's Outlook.

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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.