The fire broke out around 8:15 p.m. Thursday night. Five structures were threatened by the blaze.
The Napa County Sheriff's Office said that no evacuations have been ordered but that roads will be closed as firefighters work to contain the fire.
The fire is now 75 percent contained and the forward spread of the fire has been stopped.
Several people are smelling smoke in four counties in the Bay Area.
Firefighters hope to have it fully contained by 6 p.m.
No injuries have been reported.
Bay City News contributed to this report.