SAN FRANCISCO — Large swaths of central and Northern California were without electricity Wednesday as the state’s largest utility began cutting power as a precaution against sparking wildfires.
The utility, Pacific Gas & Electric, said that as of early Wednesday morning power had been cut to around 500,000 of the 800,000 customers who will be affected. Once fully implemented on Wednesday the outages will span from the doorstep of Silicon Valley to the foothills of the Sierra.
Extreme winds are expected Wednesday and Thursday. Peak wildfire season has arrived in California, with a combination of high winds and low humidity creating conditions for potentially catastrophic fires.
Power lines owned by PG&E were blamed for several large wildfires in recent years, with strong winds and untrimmed vegetation hastening the damage.
Karleisa Rogacheski, a meteorologist in the National Weather Service’s Sacramento office, said that Wednesday’s winds were expected to be the strongest since the North Bay fires two years ago.
“The weather pattern and fuel conditions are pretty darn close,” she said.
In San Jose, the country’s 10th-largest city, officials warned Wednesday morning that many traffic signals would go dark at noon, when the second wave of power cuts was due to take effect.
Motorists will be left to navigate intersections on their own in most affected areas, officials said, a daunting prospect in a city that has gnarled traffic on the best of days.
“Avoid driving if at all possible,” said Charles Jones, the vice mayor of San Jose.
Kip Harkness, the city’s deputy city manager, said he was most concerned about elderly residents and those who rely on medical equipment. He urged residents to check on their neighbors.
“This event can be very scary and it can affect a lot of people,” Harkness said.
PG&E estimates 38,000 customers will be affected by the power outage in Santa Clara County, where San Jose is located. But an entire apartment building can be considered a single customer. Harkness estimated that as many as 200,000 people could be without power in San Jose alone.
The company has been found responsible for dozens of wildfires in recent years, including the state’s deadliest, an inferno in and around the town of Paradise in November that killed 86 people.
Over the summer the utility turned off power to less-populated areas in Northern California, but this shut-off is by far the company’s most extensive, affecting large parts of the San Francisco Bay Area.
More than half of all counties in California, 34 of 58, are expected to be affected by the power cut, according to PG&E, one of the country’s largest utilities.
PG&E anticipates it will begin turning power back on starting Thursday, when winds subside.
But reenergizing power lines is a tricky process. Sumeet Singh, a PG&E vice president, said in a briefing Tuesday night that technicians will need to inspect “every inch” of line before restoring power. That could take as long as five days, he said.
Shoppers emptied supermarket shelves of batteries, water, and other essentials, with many hitting the stores Tuesday night and early Wednesday while power was still on.
In the small beach town of Montara, just down Route 1 from San Francisco, Heidi Kay and her partner, Steve Christie, had charged their phones, laptops, and external batteries Wednesday morning. They took inventory of their few supplies, which amounted to little more than granola bars, oatmeal and fruit, said Christie, 49, who works for a winter sports equipment company. “We haven’t really stocked up on anything,” he said.
Kay, 39, who works for walmart.com, was checking social media for updates on the power outage, which was expected in the afternoon. She had driven to the nearby town of San Bruno to buy a few groceries after finding the Target near her office had been practically stripped bare.
The hardware store was also “out of everything,” she said, so Montara residents were taking matters into their own hands on the neighborhood social app Nextdoor.
“Everyone on there is in search of a generator,” she said. “It’s mad chaos.”
The main mass transit systems serving the San Francisco Bay Area, BART and Caltrain, said they would maintain service.
A number of schools in San Jose and Oakland said they would close for as long as there was no power. The University of California Berkeley canceled classes Wednesday.
The East Bay Municipal Utility District, a water utility, said its pumping capacity would be affected and urged customers to minimize water use and turn off irrigation systems.
PG&E, which filed for bankruptcy protection in January in the face of tens of billions of dollars in wildfire liabilities, has been repeatedly castigated and admonished by a judge overseeing an effort to improve the company’s safety culture and remove vegetation near its electrical lines.
The deliberate power cuts have been described by PG&E as a way to lower the risk of fire while the company proceeds with its vegetation-trimming program. But by no means does it remove the risk of fires entirely.