top of page

CALIF EMERGENCY FLEX ALERT: Conditions on the electric grid are strained due to extreme heatwave

Please check map to link of outages in your area; as heat wave intensifies, an even greater reduction in energy use is needed to maintain reliability

By ONME Newswire

FRESNO, Calif. – As parts of northern and central California, such as the Sacramento, San Jose and Los Banos areas, are experiencing power outages due to soaring, high temperatures, other areas of California are 20 to 30 degrees higher than their average temperatures during this time of the year. California has gone to a "FLEX ALERT" status.

A Flex Alert is a call for consumers to voluntarily conserve electricity when there is an anticipated shortage of energy supply, especially if the grid operator needs to use reserves to maintain grid integrity. When consumers reduce electricity use during a Flex Alert, it can prevent more dire emergency measures, including rotating power outages.

These alerts are issued by the California ISO, a nonprofit, public benefit corporation, which manages the flow of electricity along the high-voltage electric grid for 80 percent of California. The state’s three investor-owned utilities, Pacific Gas & Electric, San Diego Gas & Electric, and Southern California Edison, are responsible for delivering electricity from the high-voltage grid to its customers.

Just before 6:00 PM PST, an emergency alert went out to mobile devices and phones warning residents of the possible outages to come, asking people to voluntarily conserve energy to reduce strain on the electricity grid.

Record-breaking temperatures are leading to historic high forecasted demands for power, putting even greater strain on the California Independent System Operator (ISO) electrical grid and significantly increasing the likelihood of rotating outages unless consumers can reduce their energy use even more than they have so far.

“This is an extraordinary heat event we are experiencing, and the efforts by consumers to lean in and reduce their energy use after 4 p.m. are absolutely essential,”

said Elliot Mainzer, the California Independent System Operator’s president and CEO.

“Over the last several days we have seen a positive impact on lowering demand because of everyone’s help, but now we need a reduction in energy use that is two or three times greater than what we’ve seen so far as this historic heat wave continues to intensify.”

Photos courtesy of Julia Dudley Najieb - ONME News

The ISO declared an Energy Emergency Alert 1 (EEA) Monday morning from 5p to 9p. That emergency designation signals to utilities and consumers that all resources are committed or forecasted to be in use, and that energy deficiencies are expected. A Flex Alert urging consumers to reduce their power use in the late afternoon and evening is also in effect tonight, marking eight consecutive days the call to cut demand has been issued.

An EEA 3 has been declared; if necessary, the grid operator can now order rotating power outages to lower demand and stabilize the system. Utilities can now make the determination of how best to spread and rotate the outages across for their service territory, with the goal of keeping them as short as possible. If outages are initiated, consumers can expect to receive notifications from power providers on areas affected and time duration.

Bay Area and Central Valley residents can also check to see if they are a part of the outage map for the rolling blackouts here. Here is the current outage map for PG&E customers: PG & E Emergency Site Outage Map. Also, PG & E has different suggestions on their website on simple ways to conserve energy, save money and help ease the burden on the power grid.

For two days in August 2020, outages affecting about 800,000 homes and businesses lasted anywhere from 15 minutes to about 2 ½ hours, marking the first-time outages were ordered in California due to insufficient supplies in nearly 20 years.

“We never want to get to that point, of course,” Mainzer said, “but we want everyone to be prepared and understand what is at stake. We can’t control the weather, but we really can bend the demand curve and get through this successfully if everyone doubles down and reduces their energy use as much as possible.”

For more information, see Rotating Power Outages fact sheet.

Tonight’s peak electricity demand is currently forecast at more than 52,000 megawatts (MW), a new historic all-time high for the grid, as the state endured the hottest day in this prolonged, record-breaking heat wave. Tuesday's peak demand showed at 51,145 megawatts (MW), which set a new record from the previous high of 50,270 MW in 2006. For context, see Peak Load History report.

Consumer and commercial demand response, including Flex Alerts, has been helping to extend tight resources over the past week, with a load reduction of around 1000 MW for each of the past several days, with more now needed as the heat continues to increase.

Before a Flex Alert takes effect, consumers are encouraged to pre-cool their homes and use major appliances earlier in the day, when solar supplies are abundant. Cooling homes in advance minimizes discomfort during the Flex Alert.

Reducing energy use during a Flex Alert can help protect the power grid during tight supply conditions and prevent further emergency measures, including rotating power outages. Turning your thermostat to 78 degrees or higher, health permitting, not using major appliances such as your dishwasher or washing machine and turning off all unnecessary lights are among the most effective ways to reduce residential energy use.

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

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.

What to do before a FLEX ALERT:

Before the Flex Alert, Californians should:

  • Pre-cool your home or workspace. Lower your thermostat in the morning. As the temperature rises outside, raise your thermostat and circulate the pre-cooled air with a fan.

  • Use major appliances, including:

    • Washer and dryer

    • Dishwasher

    • Oven and stove for pre-cooking and preparing meals

  • Close your shades. Sunlight passing through windows heats your home and makes your air conditioner work harder. Block this heat by keeping blinds or drapes closed on the sunny side of your home.

During the Flex Alert, Californians should:

  • Set your thermostat at 78 degrees or higher, health permitting. Every degree you lower the thermostat means your air conditioner must work even harder to keep your home cool.

  • When it's cooler outside, bring the cool air in. If the outside air is cool in the night or early morning, open windows and doors and use fans to cool your home.

  • Avoid using major appliances.

  • Turn off all unnecessary lights.


bottom of page