Californians urged to prepare for continued high heat

More extreme heat is forecast, which could drive up energy demand

FOLSOM, Calif. – To help the public prepare for the need to conserve energy, the California Independent System Operator (ISO) is issuing this heat bulletin in anticipation of persistent above-normal temperatures and increased electricity demand in much of California and the West today and Thursday, July 11.

After a slight brief reprieve from historic extreme heat that has impacted much of the state for more than a week, temperatures in California are climbing up again, with the hottest day forecast on Thursday. The forecast continues to indicate sustained temperatures that are well above average in California, and the Central and Desert Southwest regions of the Western US.

California is expected to see increased temperatures the next couple days as a ridge of high pressure builds, leading to forecasted temperatures of 101-112 degrees in the interior of the state. In addition to a warming trend along the Northern California coast where temperatures are forecast to be near 100 degrees in San Jose, Oakland and San Francisco are expected to reach into the low 80s. Southern California coastal temperatures will also rise the next couple days, leading to forecasts near the mid-to-upper 80’s, with potential for low 90’s in some areas.

Desert regions are forecast with little change in temperatures over the next several days, with 109-113 degrees at Lancaster/Palmdale Wednesday through Friday and about 117-120 degrees in Palm Springs.

At this time, the grid is stable, and we will continue to monitor conditions carefully. As the heat persists, it’s important to emphasize that events that linger for many consecutive days can overtax generators running at high outputs for long periods, causing outages and reduced generation. Wildfires are also active in many areas of the state, which can pose a threat to generators and transmission lines. And the hotter weather is now extending to other areas of the West, which could limit the potential for importing energy.

If weather or grid conditions worsen, the ISO may issue a series of emergency notifications to access additional resources, and prepare market participants and the public for potential energy shortages.

The ISO could also issue a Flex Alert encouraging consumers to voluntarily reduce electricity use from 4 p.m. to 9 p.m. on certain days. Flex Alerts are typically issued for the subsequent day based on day-ahead market outcomes. Learn more about conserving energy or sign up for text notifications at

The ISO continues to closely monitor conditions and will provide updates as necessary.

To stay current with forecasted supply and demand conditions, and monitor grid status, visit the ISO’s Today’s Outlook, download the free ISO Today mobile app, and follow us on Twitter/X at @California_ISO.


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California ISO | 250 Outcropping Way | Folsom, CA 95630 |


The California Independent System Operator (ISO) is a nonprofit public benefit corporation dedicated, with its partners, to continuous improvement and secure operation of a reliable grid operated for the benefit of consumers. It provides comprehensive grid planning, open and nondiscriminatory access to one of the largest networks of high-voltage transmission power lines in the world, and operates a $9 billion competitive electricity market. Recognizing the importance of the global climate challenge, the ISO is at the forefront of integrating renewable power and advanced technologies that will help provide a sustainable energy future efficiently and cleanly. The Western Energy Imbalance Market (WEIM) is a real-time wholesale energy trading market that enables participants anywhere in the West to buy and sell energy when needed. The WEIM Governing Body is the governing authority designed by regional stakeholders and has shared authority with the ISO Board of Governors to resolve rules specific to participation in the WEIM.

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