The subregions of Sonoma County are its legally recognized winegrowing areas, usually discussed as American Viticultural Areas rather than a single unified hierarchy. These appellations reflect major differences in coastal exposure, fog, elevation, soil, rainfall, wind, and temperature across one of California’s most geographically varied wine counties.
Key areas include Russian River Valley, Sonoma Coast, West Sonoma Coast, Alexander Valley, Dry Creek Valley, Sonoma Valley, Knights Valley, Rockpile, Moon Mountain, Petaluma Gap, Fort Ross-Seaview, Chalk Hill, Green Valley, and Los Carneros. Their importance lies in showing Sonoma’s diversity: cool coastal zones favor Pinot Noir and Chardonnay, while warmer inland valleys and mountain sites support Cabernet Sauvignon, Zinfandel, Syrah, Merlot, and other structured red wines.