The fire was reported at 11:08 a.m. in a grassy area behind the end of Seventh Street in the San Marin neighborhood.
Crews had the fire under control by 11:30 a.m., Novato Fire Protection District Battalion Chief Jeff Veliquette said.
The one-alarm fire charred about a 5-acre area of grass, brush and trees, Veliquette said.
He said crews would be monitoring the area for the next few hours, clearing away dead trees and brush and watching for hot spots.
No one was injured in the fire, and nearby homes were not in danger as the fire was about 1,000 feet from the nearest backyard, Veliquette said.
Fire officials are still investigating what sparked the blaze, but Veliquette said it appears the cause may have "a human component."
Firefighters found some personal belongings in an area along the ridge that may be connected to the fire, he said.
Veliquette noted that "the grass and brush up here is extremely, extremely dry," which he said makes for extreme fire danger at this time of year.