Washington State
Washington State is located in the Pacific Northwest of the United States, immediately north of Oregon. Almost all wine production occurs in the hot, desert eastern part of Washington, although there is some viticulture in the cooler, more humid west. The Cascade Mountain Range defines the geography of the region by acting as a barrier between the two sides. The mountains create a rain shadow, effectively blocking most precipitation.
Columbia Valley
Columbia Valley, in the southeast corner of Washington state, is one of the largest official wine growing regions in the United States. It is centered around the Columbia River and its tributaries: the Walla Walla, Yakima and Snake rivers. The valley lies in a rain shadow caused by the Cascade Mountains, which contributes to its dry continental climate. Here, warm days are followed by cool nights, ensuring a long and regular growing season during which the grapes achieve full maturity while retaining their vital acidity.