Wednesday, August 20, 2025

Southern California Grid Stable as Region Braces for Record-Breaking Heat Wave

The state’s electrical system remains resilient as extreme temperatures threaten to push demand toward peak limits

Southern California’s electrical grid remains in normal operating condition with ample reserves as the region braces for the most dangerous heat wave of 2025, expected to peak Thursday and Friday with temperatures reaching up to 109º in some valley areas.

The California Independent System Operator reported early Wednesday that current demand stood at 25,677 megawatts, with 51,733 MW in available capacity and 2,426 MW in reserves. Today’s forecasted peak of 39,642 MW remains well below emergency thresholds.

“CAISO is closely watching conditions and may issue Flex Alerts if demand approaches supply limits during the heat wave,” the agency stated. The last significant Flex Alert period occurred over two years ago.

An Extreme Heat Warning has been issued by the National Weather Service for Los Angeles and Ventura Counties, effective from 11 a.m. Thursday to 9 p.m. Saturday. Urban temperatures are forecast to reach 95 to 98ºF, with overnight lows above 70ºF, offering little relief and increasing stress on both the electrical grid and public health. Woodland Hills could see highs of 109ºF.

Local utilities report normal operations. Pasadena Water & Power has no outages and recently completed scheduled maintenance on its online services from August 1 to 3.

Southern California Edison concluded Public Safety Power Shutoffs on August 15 and reports no active PSPS events in Pasadena, Altadena or surrounding areas. Emergency outage reporting is available 24/7 via utility websites and hotlines.

California’s energy supply includes approximately 45 percent renewable generation. Solar and wind each contribute 3,874 MW, with solar peaking above 21 GW daily. Battery storage exceeds 15 GW statewide, with over 10 GW available for peak evening support, including 11 GW of four-hour lithium-ion batteries. Strategic reserve programs add another 3,379 MW of emergency capacity. Natural gas remains the primary backup source, supplemented by hydro, nuclear and imports.

Residents are advised to pre-cool homes to 72ºF before Thursday, close blinds and use major appliances early in the day. During peak hours (4 to 9 p.m.), they should set thermostats to 78ºF if health permits, avoid unnecessary lighting and electronics, and shift activities to cooler parts of the day. Cooling centers are open across Los Angeles County; locations are available on city websites.

“This heat wave represents the most significant thermal stress test for California’s grid in 2025,” the report concludes, as the state continues its transition to renewable energy while relying on expanded battery storage and strategic reserves to maintain reliability.