California's electrical providers, reporting "an energy shortfall" during a prolonged heat wave, imposed rolling blackouts Friday that have impacted at least 2 million people, authorities said.
The California Independent System Operator, which manages the power grid, declared an emergency shortly after 6:30 p.m. and directed utilities around the state to slash their power loads by 1,000 megawatts. The resulting outages affected an estimated 750,000 homes.
Pacific Gas & Electric, the state's largest utility, tweeted that it would turn off power to about 220,000 customers in rotating outages for about an hour at a time. Other utilities were told to do the same.
“Unfortunately, because of the emergency nature of this, we weren’t able to notify customers in advance,” Jeff Smith, a company spokesman, said in a telephone interview with Bloomberg.
The outages occurred for 60 to 90 minutes on a rotating basis through the utility’s northern and central California service territory, he said.
The emergency declaration ended just before 10 p.m. and officials said power has been restored statewide.
“Extreme heat is really the driver behind this," said Anne Gonzales, spokeswoman for the power grid operator.
“We’re dealing with weather, clouds, wildfires … these are quickly evolving situations, quickly changing,” she said.
People cooped up in their homes in the heat and blasting fans and air conditioners to keep cool was another factor that contributed to the Stage 3 grid emergency.
The intense heat wave is expected to last through the weekend, bringing triple-digit temperatures and extreme fire danger to several parts of the state.
Excessive heat warnings for much of California are in effect through Wednesday, the National Weather Service said.
In some parts of the state, including Santa Clara, Alameda and Contra Costa counties, officials opened cooling centers for people to seek refuge in the afternoon and early evening. San Francisco officials said the city is recommending people stay home and that if the heat indoors gets unbearable, to go outside to a shady place where they can stay cool and distance from other people.
“Congregate indoor sites are not safe necessarily during COVID-19. It is better to follow other instructions during this heat wave," said Mary Ellen Carroll, executive director of the Department of Emergency Management.
The state is still grappling with the nation's highest number of coronavirus case, surpassing 600,000 infections in recent days.
California last faced mandated rolling blackouts in 2001.
The Associated Press contributed to this report.