Sonoma Valley AVA
Sonoma valley is a thin 25 mile long stretch that runs acorss the middle of the southern half of Sonoma county. It's bordered on the east by the Mayacamas mountain range, which separates it from Napa. This part of Sonoma benefits from the cooling influences of the San Pablo Bay, much like Napa. The hottest parts of this AVA are near Kenwood amd Glen Ellen, and the coolest parts are towards the north, closer to Santa Rosa, where the Pacific ocean moderates the climate. The soil type are quite varied, including sand, gravel, shale, and oceanic sediment. The area has about 30 wineries and growers that produce a vast array of wines.
Sonoma Mountain AVA
Sonoma Mountain AVA is sub-region of Sonoma Valley. It is in the mountain area on the western side of Sonoma valley, and has vineyards planted in a range of 1,200-1,600 feet. The most commonly grown grapes here include Cabernet Sauvignon, Zinfandel, and Chardonnay. The volcanic and gravel soil, similar to the Napa mountain areas, helps produce age-worth and expensive wines.
Sonoma Coast AVA
The Sonoma Coast AVA is a massive area, containing about 480,000 acres. It includes vineyards in the coastal area from the border with Marin County to the south and Mendocino to the north. It includes the AVA's of Chalk Hill, Green VAlley, Carneros, Sonoma Valley, and Russian River Valley. Most of the area is quite cool, and its best wines include Chardonnay and Pinot Noir.
Northern Sonoma AVA
This AVA covers many areas throughout Sonoma county, and was created solely because of the efforts of Gallo of Sonoma, which produces bulk wines from these areas.
Russian River Valley
The Russian River valley is a very cool area that produces mostly Chardonnay and Pinot Noir. The area was a large wine producing area in the latter half of the 1800's, but phylloxera and prohibition almost totally wiped everything out. This AVA also include the Chalk Hill, Green Valley, and Sonoma County AVA's.
Sonoma County AVA
This AVA is the coolest part of the Russian River Valley, due to the influence of the Pacific. The primary grapes include Chardonnay and Pinot Noir, which are often used to make sparkling wines in this area.
Chalk Hill AVA
Chalk Hill got its name from a vineyard that goes by the same name, and because of its white soil. This soil, however, is not chalk, but is actually white volcanic ash. Many of the vineyards here are located higher on the hills, above the fog line, where the temperatures are slightly warmer than the rest of the Russian River Valley. Chardonnay is the most common grape here, as well as Sauvignon Blanc, Merlot, and Cabernet Sauvignon.
Green Valley AVA
Green Valley is in the south west corner of the Russian River Valley. It produces Chardonnay and Pinot Noir that is known for it's high acidity. Many sparkling wine producers have been attracted to this and have moved to this area.
Dry Creek Valley AVA
The Dry Creek Valley is just north and west of the Russian River Valley. This area is a thin valley isolated from fog by the coastal mountains that surround it. It is a warmer area than the russian river valley, and received just enough rainfall to make growing without irrigation possible. As a result of this climate, a lot of Italian immigrants came to the area at the end of the 19th century to grow wine. They planted Zinfandel, Carignan, and Petite Syrah, many of which are still being produced there today. The soil in this area is called Dry Creek Conglomerate, which is a red rocky soil with excellent drainage.
The Alexander Valley is named for Captain Cyrus Alexander, who was one of the original people to receive land from General Vallejo after Mexico got its independence from Spain. It was established as an AVA in 1988. This is a fairly warm area, and the soils are very fertile and rich, which means winemakers must take steps to reduce yields. Most of the wine produced here is red, including Cabernet Sauvignon and Merlot. Some white wine is also produced, including Chardonnay and Sauvignon Blanc.
This AVA connects Sonoma to Napa in the North. It is a slim valley that has very hot daytime temperatures on the valley floor. At night the Russian River Valley does offer a cooling influence. Hearty red varieties like Cabernet Sauvignon are the most common grapes, but there is also some Chardonnay, Sghtghtly Sauvignon Blanc, and Pinot Noir grown in some of the cooler, slightly elevated areas of the valley at 1,100 to 1,800 feet.
Rock Pile is in the Northwest corner of Sonoma county. It's a 15,400 acre area, with lots of rocky terrain, with elevations around 800 feet above sea level. It overlaps with the northwest corner of Dry Creek. There are no wineries in Rock Pile, but there are vineyards that grow mainly Zinfandel, as well as small amounts of Petite Syrah and Cabernet Sauvignon.
Carneros actually covers areas in Napa Valley, Sonoma Valley, and the Sonoma Coast AVA's. The San Pablo bay cools this area down, and its moisture also fends off frost in the spring. The soil in Carneros is mostly clay, which helps keep yields low, and the low amount of rainfall means irrigation is a necessity.The area is known for its Chardonnay and Pinot Noir, but also produces some Merlot.