Sonoma County is one of the largest of northern California’s coastal counties. Vineyards are everywhere and it’s a geologically and climactically diverse area. To the east, the Mayacamas Mountain Range marks the boundary between Sonoma and Napa, and to the western edge of the county is the Pacific Ocean. 80 kilometres of coastline is buffered by a ridge which protects the most coastal vineyards from conditions too extreme to ripen grapes. The county contains 19 AVAs ranging from warm regions where Cabernet Sauvignon and old vine Zinfandel are capable of reaching 16% abv and above; to cooler regions that can produce lean and racy Chardonnay.\nSonoma and Napa counties enforce labelling laws requiring the county to be listed on the label regardless of whether the label already states an AVA (like in Sonoma Coast).\nUnlike Mendocino or Napa there is not an overarching AVA for Sonoma, however all 25,000 hectares under vine are included in one of the 19 AVAs within the county.\nSonoma Coast\nThe Sonoma Coast AVA is a vast appellation that spans over 200,000 hectares of land, incorporating miles of rugged coastline and extending further inland than the Russian River Valley in some places. The coolest areas of the AVA can be found in the northern reaches by the coast where altitude, exposure, cool sea air and fog, along with high rainfall, combine to moderate temperatures and provide ideal conditions for Pinot Noir, Chardonnay and cooler-styled Rhône reds. Further inland and towards the south is typically warmer and produces bolder-styled wines.\nImportantly, the West Sonoma Coast AVA which was approved in 2022 and accounts for about 20% of the vineyard plantings within the Sonoma Coast AVA, celebrates the uniquely cold, marginal, and maritime growing conditions of this region, providing distinction to those vineyards which are truly coastal. The border of this AVA hugs the coastline and runs south from Mendocino.\nFort-Ross Seaview\nThis coastal AVA was recognised 11 years before the West Sonoma Coast AVA, and is now fully nested within it. Its westernmost vineyards do not reach the coast, as the West Sonoma Coast AVA includes all potential vineyard land up to the coastline. Pinot Noir is the headline act here.\nPetaluma Gap\nPetaluma Gap is just 40 kilometres from the Golden Gate Bridge and designated as an AVA in 2018. It takes its name from a gap in the Coastal Range that stretches from the Pacific Ocean to the town of Petaluma, allowing cool winds and fogs access to the lands.\nWinters are cool and wet, and summers are warm and dry, making this a cool area with a wide diurnal range and a long growing season. The AVA spans over 80,000 hectares, of which only 1,600 or so are under vine. It is renowned for its Chardonnay, Pinot Noir and Syrah.\nRussian River Valley\nThis is a sub-AVA that lies at the heart of Sonoma County. The Russian River itself flows from Mendocino county south through Alexander Valley before cutting west at the town of Healdsburg and making its way towards the Pacific. Approximately 25 kilometres east to west and the same north to south, the AVA lies at the heart of this western kick, a sweet spot with ideal growing conditions.\nEstablished in 1983, and with 5,733 hectares currently under vine, it’s a region regarded for Pinot Noir and Chardonnay, but its varied climate also allows for the production of Zinfandel and Rhône varietals. The soils are fertile and alluvial, with plenty of the Goldridge sandy loams characteristic of the valley. Warm daytime temperatures are moderated by fog from the Petaluma Gap to the south and by the river itself.\nThe Russian River Valley grower’s association has drafted 5 unofficial sub-regions to better distinguish the diverse soils and climates: Santa Rosa Plains, Middle Reach, Laguna Ridge, Sebastopol Hills and Eastern Hills. The fully nested Green Valley AVA was established at the same time as the Russian River Valley AVA.\n\nChalk Hill\nChalk Hill is a small AVA at the bottom of Alexander Valley, mostly nested within the north-western corner of the Russian River Valley. Varietals here are dominated by Merlot and Cabernet Sauvignon. The soils here don’t contain chalk, but are chalk white in colour, hence the name.\nBennett Valley\nRecognised as an AVA in 2003, this is a gently sloping elevated valley set between three mountains in Sonoma County. It’s a small AVA, spanning over 3200 hectares in size, but with just over 260 of those under vine. The Valley enjoys a combination of rocky, volcanic soils and cooling marine influences (fog and ocean winds) allowing for long and moderate growing seasons.\nDry Creek Valley\nDry Creek Valley is one of the northern AVAs in Sonoma County, enjoying a warmer climate than those to the south, like the Russian River Valley. The area spans 25 kilometres in length and 3.5 kilometres in width, but is home to just over 3,500 hectares of vines. Established as an AVA in 1983, it’s a region best known for producing ripe and powerful Zinfandel, although some excellent Cabernet and Syrahs have more recently been gaining attention.\nAlexander Valley\nSandwiched between the Dry Creek and Knights Valleys, Alexander Valley is a warm, inland and northern AVA of Sonoma. Cabernet Sauvignon and Merlot predominate here, and the area is home to some very old material (some Zinfandel and Carignan vineyards date back to the 1890s).\nCarneros\nRecognised in 1983, this AVA spans both the Sonoma and Napa counties. The hills of Carneros are the first vineyards visible as you move north from San Francisco. The Napa side of the AVA is referred to as Los Carneros, while the Sonoma side is known simply as Carneros. It has the lowest rainfall in the Napa Valley and the soils are predominately sandy loam over clay. \nThe area is comprised of low rolling hills (elevations range from 0-215 metres) to the north of San Pablo Bay and is heavily influenced by the fog and cooling breezes. This results in conditions suitable for cool climate varieties like Pinot Noir and Chardonnay. Many sparkling wine producers are based here, Moët’s Domaine Carneros for instance.\nOther Sonoma County AVAs\nSome of these AVAs are recent additions formed to bring distinction to areas which have grown in importance over the years. Others were formed in the county’s first tranche of AVAs in 1983: Fountain Grove District; Moon Mountain; Northern Sonoma; Pine Mountain-Cloverdale Peak, Rockpile, Sonoma Mountain and Sonoma Valley.