SAN FRANCISCO (CBS SF) – A Red Flag Warning is in effect for most Bay Area hills above 1,000 feet Thursday, as low humidity and high winds lead to a high risk for wildfires.

The National Weather Service said the warning, which went into effect at 10 p.m. Wednesday night, covers the East Bay and North Bay hills, along with the Santa Cruz Mountains.

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Winds were high on most Bay Area peaks early Thursday, with officials reporting peak winds at 72 miles per hour on Mount Diablo, 66 miles per hour on Mount Saint Helena and 48 miles per hour on Pine Mountain.

The deteriorating conditions have prompted PG&E officials to notify customers in nine California counties – including Napa and Sonoma – that the company may shut off power beginning Thursday for safety. PG&E on Tuesday started sending automated voice messages, texts and emails to customers telling them of the possible power shutoff.

In a statement, Pat Hogan, senior vice president of electric operations for PG&E, said, “We will only consider temporarily turning off power in the interest of safety and as a last resort during extreme weather conditions to reduce the risk of wildfire.”

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PG&E officials said if they turn off power, crews will restore power as soon it’s safe to do so.

Despite being the month of November, a staggering 23.4 million out of the state’s nearly 40 million residents were under a Red Flag Warning as of Thursday morning.

In the northern part of the state, crews are battling the so-called “Camp Fire” east of Chico, which broke out early Thursday and scorched at least 1,000 acres in just a few hours.

The Red Flag Warning in the Bay Area remains in effect through 7 a.m. Friday.

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