SONOMA COUNTY (CBS SF) — A Red Flag Warning went into effect Monday night for the North Bay mountains and East Bay hills due to dangerous fire conditions and forecast high winds, officials with the National Weather Service said.

The warning started at 10 p.m. Monday and ends at 8 a.m. Wednesday.

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Winds are expected to be gusty Monday evening in both areas and those winds are expected to continue through Wednesday morning.

Fire danger in a region already ravaged by wildfires would be heightened by winds gusting from 30-50 mph. Of particular concern were the hills in the North Bay.

“Critical fire weather conditions are likely to develop across the region leading to rapid rates of spread for any new fire start,” forecasters warned. “Wind gusts of between 25 and 35 mph are likely in the hills of the North and East Bay late Monday night and Tuesday morning, with gusts of 45 to 65 mph possible across northern Napa and northeast Sonoma counties.”

Humidity overnight and during the day is expected to be low after the Bay Area suffered through a holiday weekend heat wave that only added to already tinder-dry conditions in the region.

A flareup at the Walbridge fire prompted new mandatory evacuation orders for residents late Monday night. The flareup happened near Westside Road and Sweetwater Springs Road.

The new Evacuation Order was issued for Zone 1D5:

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    • South of Mill Creek Road
    • North of Sweetwater Springs Road
    • West of Westside Road
    • East of Palmer Creek Road

People living in the area should leave now. There was also an evacuation warning for for Zone 1D5.

Earlier Monday, evacuations were ordered for the northern part of Willits after the Oak Fire in Mendocino County quickly grew to 700 by Monday evening.

Any fires that start will probably spread quickly, weather officials said. Residents are encouraged to follow all burn bans that are in effect.

The risk for wildfires will be the highest in higher terrain.

Also, a wind advisory was issued early Monday night for the North Bay mountains. The advisory goes into effect at 5 a.m. and ends at 11 p.m. Tuesday. The mountains could see gusts of up to 60 mph, weather officials

Due to the high risk for wildfires, PG&E officials have decided to cut power to tens of thousands of customers in the North Bay to reduce the chance PG&E equipment will spark a fire.

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PG&E officials are expected to start turning off power Monday night and have it back on Wednesday evening in the affected areas.