Fair Oaks, California. For other places with the same name, see Fair Oaks, California (disambiguation). Fair Oaks is a census-designated place (CDP) in Sacramento County, California, United States. It is part of the Sacramento–Arden-Arcade–Roseville Metropolitan Statistical Area. The population was 30,912 at the 2010 census, up from 28,008 at the 2000 census. The Fair Oaks zip code is 95628 and its area code is 916.