Wine Sonoma, California – Sonoma County is the second most popular wine district in California. It includes an area approximately 35 miles long by 35 miles wide. It contains broad flat fields, gently rolling hills and parts of the adjacent Pacific Coast. On the east, Sonoma County wine region borders Napa Valley along the Mayacamas Range. About two million years ago, volcanic eruptions deposited a series of ash and lava called the Sonoma Volcanics throughout much of Sonoma and Napa wine regions, especially along the Mayacamas Range. The western edge of the County is the California coastline along the Pacific Ocean. Sonoma County borders Mendocino County in the north and Marin County in the south. The wine appellation of Sonoma County contains more than one million acres of land of which 60,000 acres are planted with wine grapes. Sonoma has over 300 wineries, so the wine industry here is on a smaller scale than that of the Napa wine region. The top wine producers in Sonoma concentrate on producing prime wine grapes for the premium segment of the wine market. Sonoma’s climate is slightly cooler than that of Napa Valley, and it varies dramatically depending on the appellation. Offshore breezes and fogs keep temperatures cool for ocean-side vineyards. Chardonnay takes the lead as the most planted wine variety with 15,400 acres, and Cabernet Sauvignon is the next most planted wine variety with 11,800 acres. The area crushed about 166,000 tons of wine grapes or about six percent of California’s total wine type tonnage in 2004.