California Warned of Blackouts as State Bakes Under Record Heat Wave

Power demand was expected to hit record levels Tuesday night as the state suffers several days of excessive heat.

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An electronic sign shows a temperature of 121 degrees Fahrenheit

The thermometer registers 121 degrees Fahrenheit (49.4C) in Woodland Hills, California on Monday.

Apu Gomes/AFP via Getty Images

California's electric grid operator on Tuesday issued an emergency call for immediate energy conservation and warned that record demand for power may force rolling blackouts as the state swelters under a days-long heat wave.

Around 5:30 p.m. PT, the California Independent System Operator issued a level 3 alert -- its highest-level energy emergency alert before instituting rolling blackouts. The alert will stay in effect until 8 p.m., the agency said.

"The ISO is anticipating high loads and temperatures across the CAISO grid," the grid operator said in its alert. "CAISO is forecasting an energy deficiency with all available resources in use for the specified time period. Maximum conservation efforts are urged."

The state's power consumption is expected to set a record Tuesday, with the agency noting that "electricity demand is currently forecast at more than 52,000 megawatts (MW), a new historic all-time high for the grid," the ISO said in a news release late Tuesday afternoon. "As the state faces the hottest day in this prolonged, record-breaking heat wave, grid conditions are expected to worsen."

The heat wave, which started just before the Labor Day weekend, has broken temperature records, and excessive heat is expected to continue through Friday.

"Extreme, dangerous heat gripped much of the region on Monday and numerous official maximum record temperature records were tied or broken," the National Weather Service said of the San Francisco Bay Area.

In Sacramento, the state's capital, the temperature reached 115 degrees Fahrenheit (46.1 Celsius) on Tuesday afternoon, breaking a nearly century-old record. In Livermore, about 35 miles east of San Francisco, temperatures on Monday hit 116 degrees Fahrenheit -- breaking the city's previous all-time high of 108 degrees Fahrenheit set in 1950, the service said.

Gov. Gavin Newsom posted a video to Twitter on Tuesday warning that the state was heading into the heat wave's most severe period and urged residents to do all they can to conserve energy.

"Californians, you've stepped up in a big way to keep the lights on so far," Newsom said. "But we're heading into the worst part of this heat wave, and the risk for outages is real and it's immediate."