CLIMATE

The so-called “experts” said it was too risky. Their friends voiced their doubts as well. But when Oregon’s pioneering winegrowers came here from California in search of a place to grow Pinot noir and other cool climate varieties, they knew they were onto something: long, warm days languishing into crisp nights, up to 15 hours of daylight in the summer, and cooling breezes from the Pacific Ocean and Columbia Gorge to dissipate the heat. Now, Oregon winegrowers have identified the perfect places throughout the state to grow a variety of grapes where they thrive best—not just Pinot noir, but Syrah, Riesling, you name it.

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Out of the various factors contributing to the terroir of a wine, climate produces the most easily identifiable differences in wine style because it creates distinct differences in alcohol levels, acidity, body and fruit characteristics.

Climate is not weather.

The terms weather and climate are not interchangeable. One way to think about it is that climate is what you expect to happen based on past patterns and weather is what actually happens in a particular year. For instance, Oregon is a cool-climate winegrowing region, but occasionally has warm vintages due to unusually warm weather.

Dr. Greg Jones, professor of environmental science and policy at Southern Oregon University, teaches, “The ideal winegrowing climate allows grapes to achieve optimum sugar and acid levels naturally timed with flavor and tannin development to maximize a given style of wine and express vintage qualities.”

Climate is a compilation of sunlight, wind, rain and temperature. Each of these elements contributes in its own way to Oregon’s ability to produce high-quality wine.

Latitude is a primary factor in the amount of sunshine a region receives during the grapegrowing season. When the Northern Hemisphere is tilted towards the sun in the summertime, days are prolonged and solar intensity increases, raising temperatures. The further away from the equator a place is located, seasons become increasingly extreme with more solar intensity and daylight in the summer and less in the winter.

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A good rule of thumb is that wine grows best between the latitudes of 30o and 50o. Oregon resides between 42-46° N, which means that it is roughly halfway between the equator (0°) and the North Pole (90° N). Because of its northerly location, Oregon’s growing season days enjoy up to 15 hours of sunlight with 30-40 °F temperature swings between day and night. These long, warm days during the growing season are critical in the development of grapes from bud break to harvest. Oregon’s extended hours of sunlight ripen the grapes, developing flavors and creating the sugars that determine the wine’s alcohol potential, while the cool nights preserve acidity and create balance.


Wind influences grapegrowing by providing a cooling and drying force in the vineyard, preserving acidity in warm years and preventing mildew and rot in wet years. Too much wind can reduce yields through over-drying or breaking off shoots or flowering parts of grapevines.

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Oregon has two major sources of wind: the Pacific Ocean and the Columbia River Gorge. These cool, hardy wind forces are influenced by four major geological landmarks. The Coast Range to the west and the Klamath Mountains in the south temper strong winds coming from the Pacific Ocean. The Chehalem Mountains to the north block winds coming down from the Columbia Gorge into Oregon’s winegrowing regions during the growing season. However, the Van Duzer Corridor in the northern Willamette Valley is a break in the Coast Range, which allows a moderate wind from the Pacific Ocean to come blowing through the vineyards of the McMinnville and Eola-Amity Hills AVAs.


The amount and timing of rain greatly impacts grapevine growth, fruit quality, yields and disease pressure in the vineyard. The Oregon Coast receives approximately 200 inches (510 cm) of rain each year, a staggering amount of precipitation compared to the 40-50 inches (100-125 cm) in the Willamette Valley and even less in other parts of the state. The coast’s excessive rain yields bright green mosses and thriving vegetation but is far from ideal for grapegrowing. The Coast Range and Cascade Mountains block rainfall moving east from the Pacific Ocean, creating rain shadows in all of Oregon’s winegrowing regions. In fact, when traveling through the Columbia Gorge, annual rainfall decreases one inch for every mile traveled east past the Cascade Mountains.

Oregon Rainfall Map

Even in the rainiest areas of Oregon, rainfall is concentrated in the winter months so the growing seasons are typically dry. This ensures sufficient grapevine water stress during growing seasons to develop grape complexity.


Average temperature, growing season heat accumulation and extreme temperatures (such as frosts or heat waves) have a major influence on grape ripening and fruit quality. Latitude, composition and color of soil and local topography all impact a wine region’s average temperatures. These factors determine how a wine region’s climate can be classified.

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Winegrowing regions can be divided into four climate types based on growing season temperature averages (TAVG) from April through October: cool, intermediate, warm and hot. Generally, these climates determine what grapes will thrive in a given wine region because different grapes have different climate zones where they are able to grow best. The highest quality wines are produced from grapes grown in vineyard sites matched to their preferred climates.

The climates of Oregon’s winegrowing regions range from cool to intermediate and are much cooler than many Old and New World wine regions. It was for this reason that Oregon’s original wine pioneers came north from California – they were seeking a cooler climate in which to grow Pinot noir.


Pairing Grapes to Climate

While sunlight, wind, rain and temperature influence grapegrowing and wine production, how well Oregon’s grapegrowers have planted varieties matched with their ideal climates also matters in the production of exceptional quality wine. After 50 years of observation and research, Oregon winegrowers and their academic research partners have identified the varieties that do well corresponding with each AVA’s climate. Properly planted grapes in Oregon’s diverse climates produce high-quality, complex wines.

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Oregon’s cool-to-intermediate climates generally yield wines that are well balanced, elegant and nuanced with crisp, well-integrated acid. This makes them ideal for pairing with food and well suited for cellaring.