Tens of thousands of people in 12 counties braced for power failures in the Bay Area and Sierra foothills Sunday night after Pacific Gas and Electric Co. preemptively shut down electricity in anticipation of gusty winds, bone-dry weather and dangerous fire conditions across Northern California.

As of early Monday morning, 59,819 customers were still without power, officials said. The outage are affecting residents of Napa, Sonoma, El Dorado, Lake, Amador and Calaveras counties.

The move to shut down power was unprecedented for Northern California, where the impacts would be felt from remote towns, to cities such as Santa Rosa, Napa, Oroville and Auburn, and to popular tourist getaways such as Nevada City, Calistoga and Healdsburg.

Scheduled shutoffs rolled through the North Bay and Sierra throughout the evening, when the National Weather Service had forecast strong winds and low humidity at higher elevations.

Many factors played into the decision to turn off the power, including a widespread red flag warning, on-the-ground reports from workers and humidity levels below 20 percent.

The goal was to limit the fire risk posed by live utility lines that can fall in a windstorm. Damaged electrical equipment has sparked some of the most destructive fires in California history, including many that swept through Wine Country last year.

“We know our customers rely on electric service, and we would only consider turning off power in the interest of safety and as a last resort during extreme weather conditions,” said PG&E spokeswoman Megan McFarland. “Once the conditions are safe, our crews (will) work to restore power as quickly as possible.”

Some officials applauded the move, but others were upset.

Joan Sato, 69, of Clearlake (Lake County) said the breathing system she uses for sleep apnea won’t work without electricity and nobody at PG&E could tell her what was happening or how she should handle the situation.

“I’m angry for sure because it’s totally irresponsible to pull this stuff,” said Sato, who was alone in her darkened home with her 90-pound shepherd mix after the electricity went off at 8:35 p.m. “I’m going to have to drive to a hotel and stay in a hotel where there is power, but, with no lights, it’s not going to be a safe thing. And that means my dog will be sitting in the car all night. It’s not just me. It’s every damned senior up here.”

In the past, PG&E has resisted preemptively turning off power, saying it poses its own risks and could leave police, firefighters and hospitals with no electricity during an emergency.

After last year’s devastating fires, though, PG&E developed protocols detailing when and how to shut off power in the face of potentially life-threatening conditions. The utility has prepared for, but never executed, such an action.

As an added precaution, PG&E temporarily disabled devices called reclosers in the 12 high-risk counties. Reclosers automatically try to restart failed power lines using a pulse of electricity. While the devices can prevent or shorten blackouts, they have been implicated in past wildfires.

PG&E contacted residents who would be impacted, with a goal of sending customers alerts 48 hours, 24 hours and just prior to shutting off power.

The Onyx Theater, a small, independent cinema in Nevada City, closed early Sunday night after its manager, Celine Negrete, received a recorded message saying that its power would be turned off.

Negrete canceled shows — a decision that will cost the business money — to avoid having customers left in the dark midway through a screening. “We show really strong and powerful films,” Negrete said. “And I didn’t want our patrons to be interrupted by a power outage.”

Many in the community understand PG&E’s decision, Negrete said, but some are still frustrated.

“There’s a feeling that this is because PG&E didn’t take care of what needed to be taken care of in the past, and now we’re having to pay the price for that,” she said. “That’s what I’m hearing on social media really loudly.”

Most communities are expected to have power restored by Monday night, but some blackouts could last into Tuesday. PG&E will provide updates and information through social media, radio and on its website.

Officials in Sonoma County, which was hit particularly hard by last October’s firestorm, said they had geared up for losing electricity this weekend after being warned by PG&E that it might happen.

“I do believe that the community would rather PG&E take proactive action than have the possibility of a repeat of the fires last year,” said Susan Gorin, a Sonoma County supervisor. “We are very sensitized to high winds, smelling smoke, and everybody is very aware of vegetation management. Any measures the government or utilities can take to lessen the risk of a repeat of the hellacious firestorms would be gratefully appreciated by the community.”

Power companies in Southern California often have shut down power during Santa Ana winds over the past decade.

San Diego Gas and Electric began adopting safety measures after the 2003 Cedar Fire, which burned 273,246 acres in San Diego County. The utility has created a fire safety network, including 170 weather stations, and has shut down power 17 times during high winds since 2007.

“With so many fires pinpointed to electrical lines, when we have nights where winds are going to be 50 or 60 miles per hour, it makes sense to me,” said David Rabbitt, another Sonoma County supervisor.

North Bay officials said their main concern about such a system is that there is ample warning and specific information about which areas will lose power and for how long. That’s especially important for the elderly on respirators.

“What’s really important is that they communicate with local community hospitals, senior citizens groups and other vulnerable communities to make sure that they understand what’s going on,” said state Sen. Bill Dodd, D-Napa, who said PG&E appears to have done just that. “I appreciate the fact that they are paying attention. I wish they were paying attention a year ago.”

The dangerous fire conditions continued through Monday morning in the North Bay and East Bay hills. In the Bay Area, the weather service is also keeping a close eye on conditions in Marin, Contra Costa and parts of Alameda counties.

With most of the north state blanketed by a red flag warning, the California Department of Forestry and Fire Protection, or Cal Fire, increased staffing over the weekend, according to the agency.

The California Office of Emergency Services sent extra fire engines, firefighters and dispatchers to parts of the North Bay and East Bay.

“Reserve engines are all staffed, aircrafts are all staffed, inmate crews are heavily staffed and can respond in moment’s notice,” said Cal Fire spokesman Scott McLean. “Look what happened a year ago. The conditions are ripe right now, and we all need to pay attention and be cognizant.”

Joaquin Palomino and Peter Fimrite are San Francisco Chronicle staff writers. Email: jpalomino@sfchronicle.com, pfimrite@sfchronicle.com. Twitter: @JoaquinPalomino, @pfimrite