As red-flag fire conditions bore down on Santa Cruz County, the Bay Area and Northern California, a planned shutdown of electricity by PG&E was set that could affect more than 22,000 customers, as well as five polling locations, on Tuesday evening, the utility said.

One voting location in the East Bay was closed at midday Tuesday over safety concerns. The others were awaiting confirmation Tuesday afternoon of whether their power grid sections would be shut off.

The public safety power shutoffs were expected amid increasingly stronger offshore winds that have generated a red flag warning for severe fire danger throughout the region, set to last from 11 a.m. Tuesday until 7 a.m. Thursday. Winds are likely to blow regularly between 25-35 mph and could gust as high as 50 mph in higher elevations.

The winds are forecast to be the strongest in the North Bay Mountains, according to the National Weather Service. Winds there are expected to gust up to 60 mph below 2,500 feet and in excess of 70 mph above that elevation. The weather service said it recorded 62 mph gusts before noon Tuesday; it already had issued a wind advisory beginning at 4 p.m.

“The strongest winds we anticipate will be Tuesday night into Wednesday morning,” NWS meteorologist Dial Hoang said. “That obviously will contribute to the fire danger.”

The offshore winds were expected to dry out much of the moisture received from rain a week ago, and the weather service said the relative humidity figures are expected to be no higher than 15%.

The utility originally said the shutoffs would affect 15,000 customers and three tribal areas over 17 California counties, but the numbers eventually increased to 22,000 customers and four tribal areas. Most customers are in the higher elevations of the East Bay, the North Bay and the Sacramento Valley. Areas in the Santa Cruz Mountains are included in the list of potential shutoffs.

The power shutdown may include Lakeside Elementary School on Black Road in Los Gatos, a polling location for Tuesday’s election. PG&E said Tuesday morning that power to that location as well as four other polling locations, wouldn’t be cut off until after the polls’ scheduled closing time of 8 p.m. The utility said it has temporary generators for the locations in case they’re needed.

“We know losing power is disruptive any day of the year, and especially on such an important day as (Tuesday),” PG&E senior vice president Mark Quinlan said in a statement. “We’ve been preparing for Election Day for over a month and taking extraordinary measures to prevent outages at voting and tabulation centers and pre-staging resources to restore quickly any service outages.”

The other polls that are in the scope to be closed include three in Solano County — the Moose Lodge on Canyon Road, Orchard School on North Orchard Avenue in Vacaville and the Girl Scout House on Hillridge Drive in Fairfield — and the Calpine Geothermal Visitor Center on Central Park Road in Middletown of Lake County.

Election officials contacted Monday by the Bay Area News Group said they were prepared for power losses with backup equipment and generators.

Oakland Fire Department spokesman Michael Hunt confirmed late Tuesday morning that a polling location at Joaquin Miller Park was closed due to safety concerns, although it was not subject to a planned power shutoff. The Alameda County Registrar’s Office said voters who went to that location could cast their ballots at Montera Middle School at 5555 Ascot Dr., or drop off mail-in ballots at the drop box at Woodminister Market. 5000 Woodminister Lane.

The utility said none of the state’s tabulation centers were on a power grid section where a shutdown may occur. They said customers in line to have their power cut have started receiving notifications by email, text or phone call and urged anyone with questions to check a link to the shutdowns on their web site.

Staff writer Nollyanne Delacruz contributed to this report.