Information about Appellation

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California

North Coast

Napa Valley

Carneros

Sonoma county is the second area in California to have a concentration of quality wineries. It is cooler than Napa. Sonoma is sometimes divided into Coastal Cool and Coastal Warm regions according to the presence of fog, but this can change over periods of time, moving a region from one type to the other. The Coastal Cool regions make Chardonnay and Pinot Noir, the Coastal Warm Cabernet Sauvignon and Sauvignon Blanc. The region of Carneros at the bottom of the valley forms a bridge to Napa. The largest and most prolific wine-producing county North of San Francisco, Sonoma has six fertile valleys located between the Napa Valley and the Pacific Ocean. Going from North to South, they are Alexander Valley, Dry Creek Valley, Knights Valley, and Russian River Valley. The output is comprised of almost equal quantities of red and white wine. The climate ranges from warm in the North to cool in the South, where the refreshing effect of ocean breezes is significant, though progressively diminishing further inland. Fog penetration is more prevalent in the South around Petaluma, but rarely penetrates the Sonoma Mountains that protect the Sonoma Valley in the Southeast of the county. There are two major valley systems with significantly different orientations. The Russian river passes through the Alexander and Russian River Valleys and flows directly into the Pacific Ocean. Sonoma river drains through Sonoma Valley into San Francisco Bay. The vines grow at a height of approximately 120 m on flat land, particularly in the Russian River Valley, Alexander Valley and Dry Creek, or on the gentler lower slopes. Slightly steeper slopes are now being cultivated in the Sonoma Valley. Soils vary greatly, from fertile loams in the Sonoma Valley and Santa Rosa areas, to highly fertile alluvial soils in the Russian River Valley. A gravelly Soil occurs in Dry Creek and volcanic soils are found in the vicinity of Mount St. Helena. Because of the volume of its production, Sonoma was little more than a source of blending wine until the late 1960s. Quality winemaking began in the 1970s. Bulk winemaking is still important in the Russian River Valley, but "boutique" wineries specializing in premium varietals are increasing (where Chardonnays and Pinot Noir are successful).

Los Carneros AVA sits at the Southern junction of the Sonoma and Napa Valleys. Climate is determined by the mountains and by proximity to the San Pablo and San Francisco bays; morning fog is cleared by afternoon winds. It concentrates on Chardonnay and Pinot Noir (together >85% of plantings), and in the 1990s was the largest producer of Pinot Noir in the United States (until it was overtaken by Willamette Valley in Oregon and the Southern Central Coast of California). There are a relatively small number of producers, each with sizable holdings. It has two main soil types: yellow-brown soils with seashells giving high calcium content; and black soils that are free of fossils and more acidic. Both have a high clay content; this is controversial, with some believing that its good water retention compensates for the low rainfall (<20 inches annually), but others believing that it prevents the vines from putting out deep roots.