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The PacNW Wine Regions’ Climatic Challenges and Benefits

© Eric Cook

There are isolated places in the hills and dales of the NW that have known vines for more than 100 years, and they are the exception rather than the rule. Phrases like "Black Freeze" were coined from the seasons that froze the vines back to their roots and successfully stunted the PacNW vinifera industry for most of the twentieth century.

Like every climate, there are those pockets of agriculture which are sheltered or drained just right to avoid the climate's extremes, but they are always the few. More often, grape growers turn to other means for dulling the edges of climate. It is no different in the Northwest, and happily, that stress brings out the best in the vines, the wines and the people who raise them.

CLIMATE

In Washington's AVAs (American Viticultural Area) and Idaho, the climate is decidedly continental, that is, because they are not moderated by large bodies of water, their temperature spectrums are greater, generally getting much colder than maritime climates. Oregon's Willamette Valley is a textbook maritime climate by its proximity to the Pacific Ocean's air currents and humidity.

Continental and maritime are broad, general adjectives for the climates that comprehend a vast array of meso-climates and micro-climates, which in turn have the greatest impact on individual vines and the resulting wines, but these are useful enough distinctions for understanding what makes the styles of NW wine unique, flavorful and of broad use with meals.

CHALLENGES OF CLIMATIC SITUATION

While freezing temperatures have long been a major source of concern for the area's grape growers, some growers have offset this threat by training the vine trunks into a fan shape, that they may be more easily buried. Burying vines is, at best, back-breaking and expensive work, though effective. Other growers use a vine's reserves of carbohydrate to offset the threat. Carbohydrate reserves are built up by the vine near the end of the growing season to act like a "blood thickener" for the vines, making it harder for them to freeze to the core. Levels of carbohydrate are maximized by appropriate thinning, and pruning of the vine according to its variety. Moreover, some cover crops take enough water to inhibit late-season vine-growth which will maintain the level of carbohydrate, so irrigation techniques can also be employed intelligently.

More obvious ways of avoiding killer freezes include employing windmills in the vineyards as can be witnessed at Kiona's and Hyatt's estates, among others. They will move the air sufficiently to keep the temperature from "settling" on the vines, while not fast enough to cause a significant wind chill factor. Jancis Robinson notes that helicopters may be used to the same effect, though it's doubtful anyone with the resources to employ a helicopter made their money producing wine! Another technique employs stoves interspersed through the vineyards, burning the prunings of the vines, wood and sometimes coal.