Somis is an unincorporated community in Ventura County, California. It was established in 1892 by Thomas Bard and D.T. Perkins on a portion of the Rancho Las Posas Mexican land grant. Somis is in the Las Posas Valley on the south bank of Fox Barranca, just west of Arroyo Las Posas. For statistical purposes, the United States Census Bureau has defined Somis as a census-designated place (CDP).
The name of this townsite is derived from the Chumash term śo mís, meaning “water of the scrub oak.” There was a Ranchería named Somes noted in records from 1795 and 1796.Like many of the farms on the adjacent Oxnard Plain, the crops of corn, wheat and barley grown here were shipped through the wharf that had been constructed in Hueneme in 1871. Agricultural products were able to be shipped by rail when the line from Los Angeles to San Francisco was routed through the valley and a stop was established adjacent to the community. The current spelling of the name was established when the railroad came through.