Washington State Climate & Growing Conditions

In this section, you will have the chance to dig a little deeper into why Washington is one of the world’s great wine regions. What makes Washington State wine so unique – and does that only apply to grape growing conditions? We think not. There a lot of wonderful aspects to our industry which contribute to the wine excellence you taste in the bottle. 

Washington State Climate & Growing Conditions

The Weather

Sun - Great wine grapes need sun to aid in the production of sugars (via photosynthesis), color development and heat accumulation for overall physiological ripening.  How much sun does Eastern Washington receive?

  • While the growing season is slightly shorter from beginning to end than more southerly wine regions, the number of sun hours received in Eastern Washington is equal due to incredibly long days at such a high latitude – receiving 16 hours of sun at the summer solstice.
  • There is sun 300 days a year.
  • The angle of the sun is similar to the great wine regions of Northern Europe, as they share similar latitudes.

Dry Growing Season - Eastern Washington is one of the highest latitude wine regions in the world.  Similar areas elsewhere tend to be on the cusp of cool, rainy weather in the spring and fall, making viticulture difficult – especially at sensitive times like harvest.  Eastern Washington is dry enough to be categorized as a Continental Semi-Desert.  Why?

  • The majestic north south running Olympic and Cascade Mountain ranges in the Western portion of the state combine to stop the clouds rolling in off of the Pacific Ocean - known as a Rain Shadow Effect.  Eastern Washington is the highest latitude wine region to experience this phenomenon in the New World (read: not Europe).
  • Only 7 to 12 inches rain fall in Eastern Washington.
  • Common vineyard fungal disease such as oidium (powdery mildew), peronosperal (downy mildew) and grey/black rot require a humid environment.  Due to its arid climate, Eastern Washington is remarkably fungus free; as a result, very few chemical based anti-fungicides are required, leading to sustainable vineyard practices that leave vibrant, healthy, lively soils and water sources.

Water - Eastern Washington has the good fortune of having incredible water sources to rely on for irrigation in such an arid region.  This allows absolute control as to when the vine is given moisture and how much is given, which contributes to grape ripeness, lack of sugar dilution, canopy management and dehydration controls at vital moments during its growth. 

  • Mountain Rivers:  The Columbia Basin benefits from snow melt runoff.  The massive Columbia River in Eastern Washington is the most obvious example, combining the Cascades, Rockies and Blue Mountains runoff to the 15th largest river in the United States at 1,214 miles in length.
  • Underground aquifers run through levels of basalt lava flow, and can be tapped via wells for water reservoirs.  World class, technologically controlled/timed irrigation systems are utilized to influence the growth of many vineyards.
  • Drip irrigation is most common, but some overhead spray irrigation also exists. 

Daytime Air and Soil Temperature - Consistently warm daytime air and soil temperatures during the growing season are critical to producing the grape varieties that Washington State specializes in, helping with the physiological ripening - including skin color, skin and pulp texture, seed color and texture, tannins and other flavor compounds.  Cold (though not freezing – see “Vital Issues” at the end of this section) during the winter months are ideal for vine dormancy, allowing the plant to rest and restore.

  • Average daytime high vineyard air temperatures for June 1 to October 15:  78 degrees Fahrenheit.  During the all important August/September months, that climbs slightly higher to 84 degrees Fahrenheit.
  • Average daytime high temperatures for December 1 to March 1: 32 degrees Fahrenheit. 
  • In addition to allowing proper dormancy, these cold winter temperatures kill many vineyard disease carrying pests such as phylloxera, moths, mites and nematodes.  This makes Washington vineyards remarkably pest free.  As a result, very few chemical based pesticides are required, leading to sustainable vineyard practices that leave vibrant, healthy, lively soils and water sources.

Diurnal Shift: Day to Night Temperature Variability - One of the greatest natural phenomena for growing grapes which end up balanced between ripe sugars (which will equate to alcohol in the wine) and crisp acidity is a difference between day time and night time temperatures – or, diurnal shift.  Washington State has some of the most dramatic fluctuations of any wine region in the world.

  • There is up to 40º F difference between high day and low night time temps!
  • Malic Acids generally dissipate through respiration from the grape in constant warm temperatures.  Cool evenings preserve the acid, which translate through fermentation to wine and adds freshness and balance. 
  • Resultant acid in the wines is natural – and seems a bit more integrated than the types added in the winery.

Different Microclimates - Eastern Washington has 13 separate AVA’s  covering over 50,000 acres of vineyard land varying from 100 feet above sea level to 1000 above sea level with all degrees of aspect to the sun.  There are cool sites, warm sites, wetter sites, windy sites, hilly sites, flat sites…all providing different ripening cycles and styles of wine. 

  • Exceptional diversity of grapes grown in the state

Vital Challenges

  • Winter Freeze:  Eastern Washington faces sustained winter freezes low enough to kill vines to the ground once every 7 years or so.  Methods such as layering (planting a living vine below the ground level for protection) are employed to combat this problem.
  • Global Warming:  A fact of life starting in the late 1990’s, this trend looks to continue, challenging existing warmer site areas to practice different canopy training methods, clonal selection and water management. Being in such intense sun, grapes face sun burn in increasingly warmer temperatures – also controlled by canopy training.  Alternative, cooler growing sites are also being explored (whether due to latitude, altitude or aspect). 

The Earth

Good (Bad) Dirt - Vines are somewhat choosy about their soils.  A combination of lack of nitrogen, strong drainage and healthy organic nutrient matter is a consensus perfect dirt.  It may be “bad” for growing almost anything else, but it is “good” for the vine.

  • Various Soil Types: A combination of mostly sandy, rocky based alluvial (meaning carried by water – see below), some windblown over periodic volcanic basalt lift and patches of clay.  Types include loess, basalt, clay, silt, loam, sandy loam. 
  • Ancient Ice Age Floods:  Imagine a 300 foot wall of water gushing at up to 80 miles an hour - 10 times the strength of all the world’s rivers combined – from a glacial lake just north of Washington/Idaho southwest to the Pacific Ocean.  More than 50 times over 2,000 years.  It happened here 15,000 years ago!  That is what a vast portion of Eastern Washington is – a dried up river bottom.
  • Poor Nitrogen Content: In these types of soils, there is a lack of nitrogen, making vines work harder to send other nutrients to the grapes and spending less energy on the foliage.
  • Excellent Drainage: Grape vines don’t do well with wet roots.  Sandy/rocky soils drain water further into the earth.  Roots dig deep to find it, working harder still.
  • Phylloxera Hates Sand: The vine killing aphid, Phylloxera (officially known as DactylasphaeraVitifoliae), cannot travel in sandy soils to reproduce, leaving Washington remarkably free of this global scourge vineyard pest.

Excellent Aspect - To take advantage of the sun exposure in the Northern hemisphere, vineyard managers plant on the slopes of the foothills of basaltic uplifts that form mini-mountain ranges on (generally) East-West axis.  Naturally, this also adds to the drainage capabilities for the odd storm in the Columbia Valley.

Vital Challenges

  • Lack of Organic Nutrients:  Eastern Washington’s soils require some fertilizing components, being so nutrient poor.  There is a strong presence of organic composts and teas being utilized throughout the state as sustainability and vitality of the soil depends upon them.  Chemical fertilizers are growing less and less prevalent.

The Vines

Own Rootstocks - Eastern Washington is one of the very few world class growing regions on earth that DOES NOT have to graft its vines onto rootstock.  Phylloxera (dactylasphaera vitifolea) is an aphid that damages roots by feeding on them and leaving them prey to disease and nutrient deficiencies - enough to kill the host vine.  It exists in 95% of the world’s quality wine regions.  As a result, these places must graft the genus Vitis Vinifera vines (which, while they count for every great wine grape in the world like Chardonnay and Cabernet Sauvignon, are prone to phylloxera) onto another type (or genus) of rootstock such as Vitis Riparia or Vitis Rupestris, which are immune to the pest and able to coexist.  While hard to prove, most wine professionals believe that there is at least some purity of flavor lost in having two different vine types forged together.  Washington State doesn’t have to do this!  As a result, the wines of Washington are 100% the grape variety planted - and that much more profound for it.

Vine Age - As vines age, more energy gets directed from the early years’ establishment of strong roots, trunks and foliage to the grape clusters.  Depending on the variety and clone of vine, peak years generally fall between 30 and 60 years of age.  The oldest of Washington’s vines are just entering their 4th decade.  If Washington wines are this great now, imagine what will become when the vines mature!

Click here for a list of grape growers in Eastern Washington.

World Class Wine Growers

Progressive Community - Washington grape growers are well aware of the youth of our industry in comparison to other established wine regions around the world.  In the need to learn relatively quickly, they realized that there was strength in unity, global information sharing, focused academic study and old fashioned hard work.  Today, Washington State is among the leaders in sustainable viticultural techniques in the world.

  • Washington Association of Wine Grape Growers: An entire organization exists that is dedicated to the enhancement of the quality of grapes and growers’ livelihoods leads. (www.wawgg.org)
  • Exposure to World: Taking a cue from our winemaking brethren from Australia and California, Washington has made great strides in reaching beyond our state lines and sharing information with the talented grape growers around the world.
    • National and international Viticulture and Enology Program graduates from such notable institutions as Washington State University, University of California at Davis, Bordeaux School of Enology and more.
    • Foreign partnerships for world class wines, including Renzo Cotarella of Antinori in Italy, Michel Rolland of Le Bon Pasteur in Bordeaux in France, Ernst Loosen of Dr. Loosen in Germany, John Duval (formerly) of Penfolds Grange in South Australia and many other contributors large and small.
  • Vineyard Practices Topnotch: Given our unique growing conditions, there are certain wine growing techniques required above and beyond what most world class wine regions do.
    • Canopy Management for early morning eastern facing vines facing the cool, gently morning sun vs. western vines facing the long, strong afternoon sun.
    • Nighttime/early morning harvest both by hand and machine to preserve higher acid levels in grapes for balance.
    • Frost/Freeze Insurance Measures such as layering (burying suckers off the trunk to protect against the cold air above ground) and some wind machines are employed.
    • Sustainable Farming with internationally respected certification bodies such as VINEA and LIVE.
  • Water Management: Washington State has the good fortune of having incredible water sources to rely on for irrigation in such a dry area as Eastern Washington.  This allows absolute control as to when the vine is given moisture and how much is given, which contributes to grape ripeness, lack of sugar dilution, canopy management and flavor development.  Growers employ state of the art technology such as Neutron Probes, Troxler Readings and Tensiometers to monitor and apply irrigation when necessary.
  • Clonal Vine and Grape Understanding: Washington is a New World leader in studying which clones ripen under the varying climatic conditions of Eastern Washington. 
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