The fire was reported around 1 p.m. on Coombsville Road near Jacks Lane, according to the Napa Fire Department.
Crews from both Napa Fire and CalFire were at the scene fighting the fire as of 2 p.m.
Firefighters were able to get the fire under control around 1:40 p.m., according to a CalFire dispatcher.
No further information was immediately available.