Barro is an unincorporated community in Napa County, California. It lies at an elevation of 236 feet. Barro is located on the Southern Pacific Rail…Barro is an unincorporated community in Napa County, California. It lies at an elevation of 236 feet. Barro is located on the Southern Pacific Railroad, 2 miles northwest of Saint Helena. This area is noted for its wine production and has numerous landmarks such as the Freemark Abbey Winery and the Wine Inn. The Napa River flows through the community.