Kincade Fire in Sonoma County continues to rage: 21,900 acres, 5% containment

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A wildfire that ignited Wednesday night in rural northern Sonoma County has exploded to 21,900 acres, with flames racing across a parched landscape amid windy conditions.

On Friday morning, Cal Fire released new information on the scope of the fire. Cal Fire reports 49 structures have been destroyed so far, and more than 2,000 people have been evacuated. No missing persons or fatalities have been reported. It is 5% contained.

The fire started during high winds, with gusts up to 60 mph, and overnight efforts on Wednesday were focused on evacuations. High winds have made the blaze difficult to contain.

"With the current fire behavior we have now we are not anticipating any [new evacuations]," said Cal Fire incident manager Mike Parkes. "However, until we have line all around this fire we urge everyone to be vigilant and be prepared to be evacuated as things change with one small gust of wind," he cautioned.

The Kincade Fire is roughly located near The Geysers geothermal power plant, northeast of Healdsburg and southeast of Cloverdale. It was reported at 9:27 p.m. in the area of Burned Mountain Road at John Kincade Road.

Between Wednesday night and early Thursday morning, the blaze more than doubled in acreage. The flames are racing through hilly terrain with elevation levels up to 3,000 feet.Firefighters are observing "long range spotting," meaning smaller fires are starting and spreading quickly.

"It’s a lot of grass and oak woodlands and then you go into trees," said Scott McLean, a Cal Fire deputy fire chief and spokesperson. "There’s a lot of rolling ground and then there’s steep topography that’s difficult to access. Then you deal with the population and structures in middle of it."

Initial radio traffic from Sonoma County Fire District indicated power lines were down but it was unclear if it was in PG&E's public safety power shutoff area zone.

Mandatory evacuations were ordered at 6:30 a.m. for the community of Geyserville. Previous evacuations are still in place, including Geysers Road to Highway 128, Pine Flat Road, and Red Winery Road. The River Rock Casino near Highway 128 has also been evacuated.

An evacuation warning is in effect for northern Healdsburg and Geyserville.

Road closures include Cloverdale Geysers Road, Geyser Road, Red Winery Road, Alexander Mountain Road, Pine Flat Road, and all roads east of Highway 128 to Geyserville.

More than 1,300 personnel and eight air tankers are helping fight the fire.

Meteorologists are closely watching the Saturday night forecast when the biggest wind event since the North Bay fires in 2017 is expected to whip mountaintops with damaging gusts of up to 80 mph.

This will be the third spell of gusty conditions in October — when the landscape is already parched — and the National Weather Service predicts it will be the most severe of the three, and likely the strongest in years.

"Confidence is high we’re going to see strong gusty offshore winds and critical fire conditions again Saturday night," said Drew Peterson, a forecaster with the NWS office in Monterey."This looks like it will be the strongest of the three… at least everything we have to look at now is telling us this. Of course, it’s subject to change with better data available closer to the event."

SFGATE will update the story as more details become available.

Amy Graff is a digital editor for SFGATE. Email her at agraff@sfgate.com.

The Associated Press contributed to this story

Full Kincade fire coverage:

— Fast-moving wildfire in north Sonoma County continues to burn

— 80 mph gusts: Strongest winds since 2017 North Bay fires forecast for weekend

—Map: Kincade Fire burning in north Sonoma County

— Cameras caught the moment the Kincade Fire started in Sonoma County

— Smoke from Kincade Fire expected to reach greater Bay Area Friday

— Health officials say N95 masks to filter wildfire smoke may do more harm than good

—Potential PG&E shut-off this weekend may impact huge swaths of Bay Area

— Our full California wildfires page