Great Washington wines can be attributed to several factors, most of which are related to unique weather and soil conditions. There are a total of 9 unique AVA's (American Vitgicultural Area's) with an additional AVA in the works, Lake Chelan. Eight of the nine AVA's are located on the eastern side of the state in the rain shadow of the Cascade Mountains with as little as 8 inches of precipitation annually. Given Eastern Washington's hot harsh summers and cold winters, this allows the vines to go into winter dormancy, and also forces the vines to struggle. Washington is one of the highest latitude growing regions, combining a true continental climate with bright, clear days during the growing season. As harvest approaches, there is a dramatic drop in temperatures, so final ripening and harvest take place in a cool environment, preserving fruit integrity and intense flavors. The unique soil characteristics of Washington are related to the volcanic region as well as the Missoula Floods. The Missoula Floods refer to the cataclysmic floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the last ice age. The floods were the result of the periodic sudden rupture of the ice dam on the Clark Fork River that created Glacial Lake Missoula. After each rupture of the ice dam, the waters of the lake would rush down the Clark Fork and the Columbia River, inundating much of eastern Washington and the Willamette Valley in western Oregon. After the rupture, the ice would reform, recreating Glacial Lake Missoula once again.

Back in 1860 nearly all of the Europe's vineyards were wiped out due to fast spreading insect phylloxera. The rate of development of this pest depends on the grape root as well as numerous environmental factors including soil and air temperature and humidity. Grafting became a common practice in viticulture after the phylloxera epidemic, by grafting the susceptible wine varieties to the resistant American species, mostly to Washington vines due to their resistance to harsh climate conditions.

The only European grape that is natively resistant to Phylloxera is the Assyrtiko grape which grows on the volcanic island of Santorini, There is some evidence to show that sandy or volcanic soils are resistant to the phylloxera insect, which would explain why Washington vinyards weren't impacted by the epidemic.