Heat, high winds prompt fire weather warning this weekend in North Bay hills

Anticipating critical fire conditions with triple-digit temperatures and strong offshore winds, the National Weather Service issued an ominous and unusually early warning for the North Bay mountains this weekend.

The Fire Weather Watch, which also covers the East Bay hills and interior valleys, runs from 11 a.m. Saturday to 8 a.m. Monday, brought on by strong pressure over the entire West Coast, the agency announced Tuesday afternoon.

Dry offshore winds with gusts in the 50 to 55 mph range are expected Saturday night into Sunday morning, “most focused over the North Bay hills,” the forecast said.

The forecast expressed high confidence for widespread weekend temperatures in the 90s to lower 100s, with Sunday the hotter of the two days.

There will be “essentially no humidity recovery,” it said, with vegetation “critically dry as observed over the last month of burning.”

Sonoma County Fire Chief Mark Heine warned of a “multi-day heat event” and predicted the Fire Weather Watch, which means critical fire weather may occur, will be converted by the weekend to a Red Flag Warning, meaning critical conditions will occur.

Heine said he expects PG&E to impose a preemptive power shutoff, but the utility has announced no plans to turn off any part of its electrical grid.

“Our in-house meteorology team continues to monitor the weather for conditions that would meet the threshold” for a shutoff, PG&E spokeswoman Deanna Contreras said.

“Right now we are tracking some dry and windy weather moving in the Sierra this weekend but have not increased the Public Safety Power Shutoff forecast to elevated at this point” in the Bay Area, she said.

High winds over the North Bay mountains triggered a PG&E power line failure that was blamed for the 77,000-acre Kincade fire last October. Hot, windy conditions two weeks ago prompted the utility to turn off power to nearly 18,000 customers in Sonoma County, affecting an estimated 45,000 county residents.

The weather service said a second burst of winds that could occur Sunday night into early Monday “looks weaker at this time,” although there would still be no ocean fog or boost to humidity.

The weather service said it was issuing the warning earlier than usual, noting that “confidence is high that (the) event will unfold though it could trend slightly stronger or weaker in terms of wind strength.”

Above-normal temperatures could continue at least through the middle of next week, the forecast said.

PG&E’s website noted Wednesday that the latest National Interagency Fire Center report favors “above normal large wildland fire potential” for most of Northern California for September and October, followed by normal potential the following two months.

You can reach Staff Writer Guy Kovner at 707-521-5457 or guy.kovner@pressdemocrat.com. On Twitter @guykovner.