Dry, windy weather forecast for the North Bay prompted the National Weather Service to issue a red flag warning for the area through 5 p.m. Thursday.

Sustained winds up to 20 mph, with gusts to 35 mph, are expected on the ridge tops in Sonoma, Napa and Marin counties late Wednesday into Thursday morning, weakening in the late morning and into the afternoon, the weather service said.

Low humidity and dry fuels will accompany the winds, creating “critical fire weather conditions,” the alert said.

Any fires that develop will likely spread fast, and outdoor burning is not recommended, it said.

On Wednesday afternoon, firefighters and helicopters were battling a car fire that spread to vegetation in the 23000 block of King Ridge Road near Cazadero.

In response to the warning, some Sonoma County fire agencies will increase staffing and deploy resources based on the needs in their areas, county spokeswoman Briana Kahn said in a news release.

The Sonoma County Emergency Management Division will be monitoring weather conditions. It has staff on call and ready to respond to any threats that could impact residents, Kahn said.

Residents can obtain safety information on Nixle by texting their ZIP code to 888-777, as well as sign up for information tailored to a particular address at www.SoCoAlert.com.

Cal Fire will be staffing all firefighting hand crews and bulldozers 24 hours a day and establishing a strike team of engines from outside the agency’s Sonoma-Lake-Napa Unit, Cal Fire spokesman Will Powers said.

Cal Fire Unit Chief Shana Jones asked residents to refrain from using outdoor power equipment until the warning period has ended, and even then using it as early in the morning as possible to avoid “increased burning conditions” during the heat of the day.

About 11 percent of the fires in the three-county area are caused by people using equipment in and around dry vegetation, Powers said.