Sonoma County extends approximately 40 miles northwest and southeast along the Pacific Coast just a short distance north of the Golden Gate. It is about 40 miles in width from east to west, extending from the coast inland to the crest of the coast range. The county is elongated southeastward into San Pablo Bay, a northern extension of the San Francisco Bay. Elevations range from sea level along the western edge and in the southeast to 3,000 to 4,000 feet along much of the eastern boundary. The Russian River flows southward into the sea. The northwest corner of the county, between the coast and the river is mountainous, with elevations ranging upward to around 2,000 feet. East of the river elevations increase again; Mt. St. Helena, on the eastern border reaches a crest of 4,344 feet. Sonoma Creek drains into San Pablo Bay through the Sonoma Valley in the southeastern corner of the county. Much of the southeastern part of the county is relatively flat farmland near sea level.
