A great majority of the AVA resides in Washington, with a small portion dipping into northeastern Oregon. It borders the Cascade Mountains in the west, shielding it from the heavy Pacific rains. This makes an arid environment for the Columbia River Basin and its tributaries.
Many factors create extremely favorable conditions for wine grapes. Lack of rain water forces vine roots deep into volcanic, loamy soils and allows farmers to control growth with irrigation. The more the vines struggle the more they concentrate on the fruit clusters, making deeper, richer wines. Days are hot and nights are cool, giving the grapes an excellent balance between acidity and sugar. Due to the northern latitude, Washington also has a long growing season (over 6 months) and more hours of sunlight. This gives farmers the opportunity to harvest later during cool temperatures. This gives the grapes more mature aromas, flavors, tannins and potential.
The fact that the valley is so massive gives many possibilities for the existence of various microclimates. This is one of the reason why Red Mountain, Yakima Valley, Walla Walla Valley, Wahluke Slope, Rattlesnake Hills, Horse Heaven Hills and Snipes Mountain are considered uniquely distinguished geographic growing areas. We will be talking about these regions while we navigate through Washington Wine Month!