Fulton, CA is located in Sonoma County. It is just to the north of the city limits of Santa Rosa, and 7 miles north-northeast of Sebastopol. Fulton has a post office with ZIP code 95439, which was established in 1871. Small city / Suburban complex in Northern California, 40 miles north of San Francisco. July, August and June are the most pleasant months in Fulton, while December and January are the least comfortable months.