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Terroir of Washington: The big picture + Columbia Valley AVA

Washington terroir is created through two main forces: the Coast and Cascade mountain ranges, and the impact of the Missoula Floods on the geology of the state.

Graphics from the Washington State Wine Commission

The mountain ranges make for eastern Washington to be hot and dry, with some spots registering less rainfall than Phoenix, Arizona.

When it comes to Growing Degree Days (defined in northern hemisphere wine regions as temperatures above 50 degrees Fahrenheit between April 1 and October 30 … each hour adds one Growing Degree) there is one element that doesn’t show on a graphic such as this. It’s the spread between the high and low temperatures during the peak months of fruit production.

Washington State vine growing regions have a wider diurnal temperature swing than places such as St. Helena, Barossa Valley, and Bordeaux. This swing from high highs to lower lows makes for grapes that preserve more acidity, making for a distinctive mouthfeel to Washington wines. Once you start to taste more Washington Wines side by side against other regions of the world, you start to pick up on this (especially with grapes such as Syrah, Merlot, and Cabernet Franc).

When looking at the mean temperature by region, what stands out is the higher high temperatures in the summer, and the lower low temperatures in the late fall. Some of the most important wine regions in Washington (i.e. Walla Walla) can have some serious low temperatures in the winter, going well below zero on occasion. Vines can handle this stress as long as it doesn’t stay that cold for days on end. Occasionally, a cold snap will kill off a vineyard, which then has to regrow before producing fruit. This ‘hardening’ of the vines in Washington is credited by many Washington winemakers with making better wines than more temperate climates.

Columbia Valley AVA

Winesearcher: Columbia Valley AVA

Wikipedia: Columbia Valley AVA

Wine Traveler: Columbia Valley AVA Introductory Guide