Washington State’s Columbia Valley AVA: A Region Designed to Craft Exceptional Wine

By Cole Swanson
March 3, 2025

It is fair for anyone to assume Washington state is just one big cloud filled with never-ending rain. Most people outside the state, and likely many residents as well, undoubtedly associate Washington with Seattle, a city ubiquitous with year-round precipitation. However, two hours east, past the Cascade Mountain range, is Eastern Washington, where the semi-arid low desert known as the Columbia Valley opposes the state’s rainy stereotype with its dry summers that are long and warm. And it is here, in this agricultural haven, where farmers take advantage of these factors, most notably viticulturists, who utilize the warmth and unique natural makeup of the land to grow grapes that will eventually produce some of the best red wines in the United States.

When discussing top-tier wine production in North America, many fall onto the leg of California’s Napa Valley AVA. But it would be unfair to leave the Columbia Valley AVA out of the conversation.

This Washington state region is known for producing high quality, bold Cabernet Sauvignon that can age in the bottle for decades, with a profile that is often compared to those from the Napa Valley AVA and Bordeaux, France – both of which are renowned for crafting immaculate Cabernet Sauvignon – because its style is considered to have flavor and structural qualities of both locations. 

This would mean notes of blackberry, cassis, licorice, eucalyptus, and green bell pepper as well as cedar spice and savory qualities. All of which are wrapped with acidity and tannins that are beautifully balanced. 

So, what allows for the Columbia Valley to be in the conversation with those two great winemaking regions? And why is there a constant discussion between which state produces the best Cabernet — Washington or California? It is thanks to the Valley’s naturally harmonious – and possibly even magical – geological factors, such as climate, sunshine, and a soil so unique it cannot be found in the same quantity anywhere else in the world.

Remember, great wine starts with farming.

CLIMATE

In my opinion, the climate of the Columbia Valley was designed for winemaking. The “rainshadow effect” and an extended period of summer sun provide a warm climate where grapes can thrive well past normal harvest times. The cooling effect of nighttime temperatures bats away the heat of the day, ensuring grapes ripen gradually and retain acidity.

The final product has properties of both Napa Valley and Bordeaux, with well-balanced structure and fruity flavors complimented by more complex notes.

It is an incredibly unique environment, especially if you enjoy nerding-out about agriculture.

Climate - The Rain Shadow Effect

We’ve established that Western Washington and Eastern Washington are opposites – wet and moderately temperate versus dry and warm. The reason for this is known as the “rainshadow effect,” a critically significant geological occurrence that allows for Cabernet Sauvignon to prosper in Washington state.

As humid, cool air from the Pacific Ocean travels east through Seattle, it reaches the Cascade Mountains. Due to its high peaks, rain is blocked and must travel above in order to continue east. As it does, clouds expand and cool. Cool air does not hold as much moisture as warm air, and so rain and snow fall onto the mountains. As the cool air passes the peaks, and makes its way to the bottom of the mountains, it will have lost much moisture and become warmer. The result is cloud dissipation and dryness because no moisture is left. 

During any summer month, travel east of the Cascades and feel the difference.

So now that we’ve travelled past the Cascades into a dry Columbia Valley, how does the rainshadow effect impact grape growing possibilities?

In a word – positively.

As we’ve established, the Cabernet Sauvignon grape needs a warm and sunny environment to fully ripen. Fortunately, because of the dissipation of clouds and the Valley’s distance from the Pacific Ocean, the climate of the Columbia Valley is considered warm continental. This means that during the grape growing season the vines will receive much consistent warmth and sunshine and no cooling influence from any water source. This will aid the ripening of sugars within the grapes and, most importantly, the phenolics (or tannins) of the grapes, which are crucial for the structure of the Cabernet Sauvignon grape.

Importantly, the Valley is warmer than Bordeaux but cooler than the Napa Valley. It also receives sunshine for a month longer than Napa (a total of 300 days versus 260 days). Because there is no water source to cool the vineyard, such is the case in Napa, these climatic conditions can be considered harmonious as they aid grape ripening without providing too much heat, which can negatively impact how the grapes ripen.

This balancing act also means Cabernet Sauvignon can hang on the vine past summer, allowing for a larger window of when winemakers may harvest depending on the style of wine they want. The longer the hangtime, the more concentrated the tannins and flavors.

Climate - Warm Continental and Much Sunshine

Climate - Large Diurnal Range

Perhaps the most impactful to creating a balanced Washington Cabernet Sauvignon wine is the Columbia Valley’s diurnal range, or the difference between daytime and nighttime temperatures.

Too much warmth isn’t always positive. As grapes ripen, their sugars develop and natural acidity lessens. To create a red wine with balance, one needs acidity, and acidity is retained in cooler environments. Again, there is no water source, such as an ocean, to provide cool wind, which would help to slow ripening and retain acidity. However, and most fortunately, during the night, the daytime heat in the Columbia Valley cools significantly.

This is known as a “large diurnal range.” Within the Columbia Valley specifically, the range is between 35°F and 47°F, meaning that during the night, it is about 35°F-to-47°F degrees cooler than during the day. The result is gradual ripening and balanced structure.

Add the extended period of sunshine to this equation and you’ll end up with a region that produces wines with delicate fruit flavor and robust tannins simultaneously.

Nature has given this wine region a reason to take its time. Winemakers are able to be patient and better analyse when it is the right time to pick, rather than having to rush to harvest the grapes under otherwise constant extreme heat.

SOILS

Talk with any winemaker and they will impart upon you the importance of soil. Soil type is monumentally impactful to vine growth and a wine’s flavors. Three primary soils directly influence how grapes grow in the Columbia Valley – basalt, loess (German for “loose”), and alluvium.

There is much information below, so what you need to know is that these soils cause the vines to struggle for water, which is important for concentrating flavors and tannins. They also reflect heat from the sun, which, much like this warm climate already does, aids ripening, even during the cool nights. Additionally, these soils, most significantly basalt, transmit iron to the vines, which creates wines that have more clarity, color, and structural stability than those not planted in it.

Now for the fun history of how we got here…

Volcanic Basalt Soils

There is no other wine region in the world that has as much basalt as the Columbia Valley AVA.

About six-to-17 million years ago one of the largest volcanic eruptions occurred, covering the Pacific Northwest with lava. Over the course of 10-to-15 million years, about 300 lava flows pushed the earth’s crust down as 6,000 feet of lava thickened on top. This carved out the land and created what is now known as the Columbia River. Soil called basalt was the result. 

The Missoula Floods Create Loess and Alluvium Soils

Traveling forward in time to about 18,000 years ago, temperatures dropped enough to create an Ice Age, forming glaciers. The Ice Age ended and a sheet of ice drifted into Idaho, creating a dam that blocked the mouth of the Clark Fork River, subsequently creating a lake 2,000 feet deep with 500 cubic miles of water. At the same time, the Glacial Lake Missoula, which stretched 200 miles east, and contained more water than Lake Erie and Lake Ontario combined, waited patiently to begin carving the Columbia Valley of today.

The tallest of these dams filled and water burst through at a rate 10 times the combined flow of all the rivers of the world, reaching average speeds of 65 miles per hour, shaking the ground. Over the course of 2,500 years the glaciers froze and thawed some dozen times as the process repeated.

The Missoula Floods cut into the basalt soil of the Columbia Valley, and the result was fine and mineral-rich loess soil that currently covers thicker soils caused by the Missoula floods, such as alluvium, as well as basalt.

How These Eruptions and Floods Impact Vines

Most vineyards in the Columbia Valley are planted on thick layers of loess, a soil that is ideal for grape growing, because it doesn’t hold water well. Viticulturists want vines to struggle to find water because it will concentrate flavors, and, in relation to red grapes, their tannins.

The below basalt, however, eventually became something to be desired, and around the year 2000 viticulturists began finding ways to plant in it because it provides heat to the vines and is rich in iron, an important element for grapes. Winemakers began planting at higher elevations on hillsides, where the amount of loess was thinner than on the valley floor. This allowed for easily ripping the loess to reach alluvium and basalt.

Whitman College studied the effects of how digging to plant vines in alluvium and basalt would affect the amount of iron and heat the vines would receive. They found that sites which had been ripped to be planted in alluvium and basalt cobbles provided the vines with significantly more heat and iron than those planted in only loess or those not made up of alluvium and basalt cobble.

How Does All This Impact the Wine?

Again, why is all of this important? These soils concentrate grape’s flavors, colors, and tannins and promote a wine with structural clarity and complexities that can age for many years.

Loess prompts the vines to struggle to find water in the below soils, which we know is important. The iron-rich basalt creates wines that have more clarity, color, and structural stability than those not planted in it. Also, the heat radiation from the alluvial and basalt cobble soils provides aid in the ripening process, even during the nighttime when temperatures are 35°F-to-47°F degrees cooler. Additionally, planting on slopes allows for more direct sunlight onto the vines, compared to the valley floor, once again encouraging ripening, while also providing a cooling effect due to elevation. 

To summarize all we have covered, without the optimal climatic conditions of the rainshadow effect, distance from the Pacific Ocean, extended periods of sunlight, a large diurnal range, and objectively unique soils, the Columbia Valley wouldn’t be in discussion for who creates some of the best wines in the country.

I can't describe why the Valley is magnificent without getting giddy.

This is a long piece, I know. But, the natural makeup of the Columbia Valley is truly astounding. It reiterates my point about wine, which is the more you learn the more you realize you know very little. There is always much to know, and I personally think continually learning about wine helps you to appreciate it that much more.

When discussing the fine wine regions of North America, it makes sense to bring up Napa first – they’re marketing department has been excellent since the Judgment of Paris in 1976, when their Cabernet Sauvignon outranked all those from France. But to be gung ho that Napa is Napa because it’s Napa closes your mind to other great regions like the Columbia Valley. Leonetti Cellar, DeLille, Upchurch Wines, Col Solare, Cayus, and hundreds more wineries makeup the wine industry in Washington state. If you like wine, the Columbia Valley is a must-visit destination.

References

Topinka, L. (2004, June 1). Columbia Plateau - Columbia River Basin - Columbia River Flood Basalts - Summary. USGS Volcanoes. https://volcanoes.usgs.gov/observatories/cvo/Historical/LewisClark/Info/summary_columbia_plateau.shtml  

Pogue, K. R. (2010). INFLUENCE OF BASALT ON THE TERROIR OF THE COLUMBIA VALLEY AMERICAN VITICULTURAL AREA. Department of Geology, Whitman College. http://people.whitman.edu/~pogue/soave.pdf

Papesh, Judith. The great Missoula flood. https://www.risingwinescollective.com/wine-community/the-missoula-flood/