At least one other appellation, Red Mountain, is on the drawing board. The Columbia Valley is geographically largest and includes the Yakima Valley and Walla Walla appellations. Therefore, the emphasis of WSU's wine and wine grape research program is based on this segment of the industry. Climatic conditions in the south central portion of the Columbia Valley of Washington state are unique compared with other wine regions of the world. Therefore, research conducted in other regions is usually not directly applicable to wine grape production h ere .
Uniqueness lies in the combination of climatic conditions that exist from season to season.
South central Washington is semi-arid. Although Vitis vinifera is native to semi-arid Middle Eastern and Mediterranean regions, these regions do not experience the cold winters of south central Washington. Dormant wine grape vegetative tissues are susceptible to freeze injury, especially if a period of cold weather is preceded by a midwinter warm spell. Although south central Washington is similar in latitude to the famous French wine regions of Bordeaux and Burgundy, those regions neither are semi-arid nor experience the cold winters. Besides winter temperatures, summer day length separates Washington from wine grape production in California.