 During the growing season Eastern Washington experiences a wide diurnal temperature variation (up to ) difference between daytime highs and nighttime lows) which allows the fruit to fully ripen while the cool nights help the vines to shut down, allowing the grape to maintain natural levels of acidity.Viticulture in Washington State is deeply influenced by the use of irrigation and the water rights associated with suitable vineyard land.Sourced from the major rivers that run through the area, most vineyards in Eastern Washington are irrigated though some vineyards (especially in the slightly wetter Walla Walla Valley near the Blue Mountains), but some have begun experimenting with dry farming.