Due to extreme heat forecasts, Flex Alert called today through Monday

September 5, 2020


Power grid operator urges conservation to avert deficits this holiday weekend

FOLSOM, Calif. – The California Independent System Operator (ISO) declared a statewide Flex Alert, a call for Californians to conserve electricity, beginning today from 3 p.m. to 9 p.m.

Flex Alerts have also been issued for Sunday, Sept. 6, and Monday, Sept. 7, to help the power grid maintain reliability during the extreme heat forecast statewide on the holiday weekend. The ISO is asking consumers to reduce energy use from the hours of 3 p.m. to 9 p.m. on all three days.

Labor Day weekend temperatures are forecast up to 15-25 degrees above normal for California, and the grid operator is predicting an increase in electricity demand, primarily from air conditioning use. Overnight temperatures statewide are projected to be at least 5-15 degrees higher than normal, which doesn't allow infrastructure to cool down.

Consumers should always be prepared for potential power outages, both planned and unplanned during heat waves, especially in extremely high temperatures that last multiple days. Hot weather can also impact generation and transmission equipment, as it runs harder and longer with less time to cool, which can cause machinery failure.

High heat is also predicted throughout the West for the weekend, limiting available import energy to serve demand.

Several wildfires in the state are also a concern because fires can take out transmission lines, or cause lines to be shut down for the safety of firefighters in the area.

Consumers can actively help by shifting energy use to morning and nighttime hours. Conservation can lower demand and avoid further actions, including outages, and lessen the duration of possible power interruptions. Conservations efforts during a heat wave on Aug. 17 and 18 were key to preventing expected power outages.

The ISO recognizes that reducing energy use during the hot time of the day is a hardship, especially for those working from home or for families with children schooling at home. However, if a large enough number of consumers conserve even in small ways, they can help grid operators avoid more serious system emergencies.

Between 3 p.m. and 9 p.m., the ISO is urging consumers to:

  • Set air conditioning thermostats to 78 degrees, if health permits.
  • Defer use of major appliances.
  • Turn off unnecessary lights.
  • Unplug unused electrical devices.
  • Close blinds and drapes.
  • Use fans when possible.
  • Limit time the refrigerator door is open.

Consumers can also take steps to prepare for the Flex Alert by doing the following before 3 p.m.:

  • "Pre-cool" their homes, or lower air conditioning thermostats.
  • Charge electric vehicles.
  • Charge mobile devices and laptops.
  • Run dishwashers, washing machines and other major appliances.
  • Set pool pumps to run in the early morning or late at night.

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.