PG&E on Friday issued a heads-up that the power may be going out in parts of northern Napa and Sonoma counties, as well as nine other counties, due to some high winds in the forecast this weekend.

We made it this far into fire season without the usual Red Flag Warnings and power shut-offs, but the weather is shifting this weekend and some potentially hazardous winds are on the way.

The Chronicle's meteorologist laid out the scenario Friday morning for the "inside slider" type storm that is coming down from Canada and expected to slide on over into Nevada. But the weather pattern, which may bring a few light rain showers to coastal areas in particular, is mostly just going to whip winds for the Bay Area.

The current onshore winds are expected to become "more northwesterly and [begin] howling at 35 mph along stretches of San Francisco Bay by Saturday," writes meteorologist Gerry Diaz. Then, the "inside-slider" slides in from the north and will "churn up strong northerly winds in California."

"The strongest winds are looking to arrive in the Bay Area on Saturday afternoon and last through Sunday morning, with widespread 25 to 35 mph winds possible across the region," Diaz says.

With that in mind, PG&E has announced its first public-safety power shutoff of the season, which the company says will affect targeted parts of Butte, Colusa, Fresno, Glenn, Kern, Lake, Napa, Sonoma, Stanislaus, Tehama, and Yolo counties beginning as early as Saturday.

Per KTVU, PG&E says that parts of northern Napa and Sonoma counties aren't likely to see the power go out until later on Sunday.

Customers who want to know if they may lose power this weekend can do an address lookup here, or you may have already received an alert if you signed up for those.

The approximate planned outage map is below, and the affected areas are small.

Image: Matthew Henry