Washington State currently has 9 AVA's, with many more currently awaiting approval.
Puget Sound
Puget Sound is the only AVA west of the cascade mountains. This area does recieve a large amount of rain, but most of it happens during the winter, outside of the growing season. In the summer the weather is mild and dry. Because of this area's loose cement subsoil retains a lot of water, the vines can survive the dry summer without irrigation. The primary grapes here are a varietal called Madeleine Angevin, and Muller-Thurgau.
Columbia Valley
Columbia valley was established as an AVA in 1984, and is Washington's largest AVA, with over 11 million acres and 17,000 acres under vine. There are many micro-climates in the valley, allowing for a great diversity in plantings. The best vineyards are located on south facing slopes where they can benefit from extra sunlight. All the other AVA's in the city, except for Puget Sound, are located inside the Columbia valley.
Yakima Valley
The Yakima valley was the first AVA in Washington, established in 1983. It comprises about 11,000 acres and about a third of the states vineyards. The valley is divided into two distinct climactic zones-- the cooler western side, and the hotter eastern side. The most common grape here is Chardonnay, with large amounts of Merlot and Cabernet Sauvignon. Yakima valley was the first place Syrah was ever planted in Washington.
Walla Walla Valley
Walla Walla is a small area in the southeast corner of Washington, and is actually shared with Oregon. It gets more rainfall than the rest of the state, thus dry farming is possible here. Cabernet Sauvignon leads the way here, followed by Merlot, Chardonnay, and Syrah.
Red Mountain
Red Mountain is a more recent AVA, having been established in 2001. It is on the easterm edge of the Yakima Valley, and is known for its red wine production, including Cabernet Sauvignon, Merlot, and Sangiovese. It also produces high quality Sauvignon Blanc. The vineyards here are all located at elevation, and take advantage of slopes to get more sun exposure. Winds from the north help to keep temperatures cool. These conditions usually produce wines that are dark, dense, alcoholic, and tannic.
Horse Haven Hills
Horse Haven Hills is just south of the Yakima Valley and bordered to the south by the Columbia river, which moderates the temperature of the area. Merlot and Cabernet Sauvignon are the most common grapes here.
Columbia River Gorge
Columbia River Gordge is just west of Horse Haven Hills, along the Columbia River. It feature volcanic bedrock and has granite and schist soil. The most successful grapes here are Chardonnay, Gewurtztraminer, and Sauvignon Blanc.
Wahluke Slope
The Slope is just north from Yakima Valley. Its most famous vineyard is the Cold Creek Vineyard, which boasts the longest growing season in the entire Columbia Valley. It has a lot of different growing areas, and thus all the major grapes of Washington state are grown here.
Rattlesnake Hills
Rattlesnake Hills is the newest AVA in Washington, established in 2006/ It covers about 1,500 acres under vine, and the altitude of the vineyards can get as high as 3,000 feet, which is the highest in the state. The soil is finer than other areas and has a neutral pH. The most common grapes here are Chardonnay, Riesling, Cabernet Sauvignon, Malbec, Merlot, and Syrah.
