The most important influence on the climate in Washington is the Cascade Moutain range, which separate Seattle from the rest of the state. On the western side, there is a great deal of rain and temperatures are cooler. But on the eastern side, where the columbia valley is located, there is very little rain, and the climate is quite arid, almost desert-like. Because of the dryness, irrigation is usually required in this area. Warm temperatures during the day, and cool temperatures at night help preserve acidity. Because of its northerly latitude, Washington also receives about 2 hours of sunlight more than California per day. Because of cold winters and sandy soils, Washington has never had a problem with Phylloxera.
Slightly more red wine is produced in Washington than white. The most common varietals include Merlot, Cabernet Sauvignon, Syrah, Chardonnay, Riesling, Sauvignon Blanc, and Semillon.
Merlot became known in the early 1990's in Washington. The classic expression of Washington Merlot is flavors of sweet cherries and berries, and aromas like spice, mint, and cedar often add additional complexity.
Most of the Cabernet Sauvignon produced in Washington is of the fairly fruity variety. The wines are age-worthy, and are often used in Bourdeaux style blends.
Syrah has been rising in popularity in Washington. The wines produced here are big, concentrated wines, with black fruit and coffee.
Chardonnay is the most commonly produced grape, and the wine produced here is usually crisp and delicate.
Riesling is found in dry and slightly sweet wines in Washington, and there is some botrytis happening, enabling the production of late harvest and ice wines.
Semillon wines are produced in Washington, and are usually designed to be drank when they are young and very fruity. Some of them can age, however, and reduce in fruit, developing nutty characteristics. Some late harvest Semillon is also produced.
Sauvignon Blanc in Washington often has herbaceous flavors, and is sometimes labeled as Fumé Blanc here.
The Washington Wine Quality Alliance (WWQA) was established in 1999 and was an voluntary effort started by winemakers, to ensure quality in their wines. The WWQA defined the term, reserve for wines, as a wine of higher quality than its other wines, which must comprise noe more than 3,000 cases, or 10 percent of the wineries total production. They also stated that wine with Washington State on the bottle must be made from grapes only from Washington state. If a varietal is listed on the bottle, the wine must contain at least 75% of the stated grape. They also forbid the use of the terms Champagne, Burgundy, Bourdeaux, and Chablis. If a winemaker chooses to participate in the WWQA, the bottle will display its logo.