Officials say road closures are in place where the fire is burning, on both sides of Berryessa Knoxville Road and Hwy 128. Additional road closures are in place at Sage Canyon Road at Lower Chiles Valley Road, Highway 128 at Moskowite Corners, and Knoxville Rd at Spanish Flat
The terrain in this area of Napa County is reportedly steep and rocky, with dry brush and pockets of timber.
According to officials, structures are threatened and additional resources have been ordered.
Stay with ABC7 News for the latest details on this developing story.