Fierce winds, dangerous fire conditions and a possible planned power shutdown by PG&E will provide the backdrop for Election Day, officials and forecasters said Monday.

“We have a low-pressure pattern set up in the lower Southwest desert, and that’s setting up some serious offshore flow in the Bay Area,” National Weather Service meteorologist Roger Gass said. “It’s generally going to be in the uphill peaks, but we can’t rule out that those gusts will be strong closer to the surface, too.”

The weather service said a red flag warning will go into effect at 11 a.m. today and extend until 7 a.m. Thursday. The interior East Bay and central coastal areas, the Peninsula, Santa Cruz and San Francisco are included in the warning.

Similar conditions last month led to a near-disaster in the Oakland Hills after a wildfire broke out near Interstate 580 and burned 15 acres.

The new warning was concerning enough for PG&E that the utility announced that it began notifying its customers that it was considering cutting power to 20,000 customers in 17 counties and three tribal areas in a public safety power shutoff.

Two polling locations are in areas that could be affected by the shutdowns, officials said: Lakeside Elementary School in Los Gatos, and the Calpine Geothermal Visitor Center in Lake County. If outages are forced by conditions, PG&E officials said, they would likely happen after voting ends at 8 p.m.

The red flag warning will allow California fire officials to stage additional personnel in dangerous areas as a preventative measure in case a fire erupts. Fire crews credited the warning for helping them to keep the Keller Fire in Oakland last month under control.

Winds heading from the northwest toward the ocean are expected to blow consistently between 20-30 mph, and the gusts could reach 50 mph, according to the weather service. The relative humidity during the daytime could be as low as 15%.

The weather service said it already had recorded gusts of 42 mph on Mount Diablo and 38 in the Oakland Hill in the first 12 hours of Monday. Winds blew closer to 15-20 mph in the lower elevations.

Those winds dried out whatever moisture remained from a pair of rain storms that hit the region last week.

“It’s gonna be critically dry,” Gass said. “The biggest peak for the winds is going to be Tuesday night into Wednesday. But we think the winds will linger into Thursday, so we extended it just in case.”

PG&E said customers in areas considered for the public safety power shutdown were notified via email, phone call and text beginning Monday and that the notifications would continue. Customers in the affected area also can go to the PG&E web site for shutdown information.

“In addition to these specific sites,” PG&E wrote in a statement Monday, “we have made plans to stage crews and emergency materials, including generators, across our service territory to quickly restore any unplanned or emergency outages that could potentially impact the election.”

Spokesperson Tamar Sarkissian said about 10,700 customers in Alameda, Contra Costa, Santa Clara, Solano, Napa and Sonoma counties could be affected by power shutoffs.

Gass said when the wind finally dies, the Bay Area may look ahead for the onset of more precipitation.

“As we get into the weekend and into early next week, rain chances enter the picture,” he said. “It’s a week out, so the confidence that we’ll definitely get some is not as high as the confidence that we have that there will be a change in the pattern.”