The student was struck by an eastbound 2007 Toyota Camry at about 8:15 a.m. as he crossed Waterman Boulevard east of Oliver Road.
The boy was not in a crosswalk and witnesses told police he failed to check for approaching traffic before entering the roadway, Sgt. Mike Mitchell said.
The teen was taken by ambulance to a local hospital. The driver of the Camry, a 39-year-old Fairfield woman, was not injured, Mitchell said.
Anyone with information about the accident is asked to call police at (707) 428-7300.