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The Unique Climate That Produces Great Wines

By: Jeff Cox

A few years ago I stood on the elevated patio of Veramonte winery in the beautiful Casablanca Valley of Chile, looking toward the Pacific Ocean. I noticed a fog bank hanging above the hills just about as far away as the ocean. “This is just like Sebastopol,” I said to myself. From Sebastopol, a town about 20 miles inland from the Pacific Ocean in Sonoma County, California, you can often see a white ridge of fog above the western hills. And for the same reason you see it at Veramonte.

We know that some of the world’s finest wines come from Sonoma and Napa counties on the western edge of the continent along California’s Pacific coast. And when you think of it, Bordeaux is on the western edge of Europe and flanks the Atlantic Ocean. And South Africa’s wine regions are similarly placed at the southern tip of Africa. And Chile makes good wine and it’s a long, thin strip of land flanking the southern Pacific. And the Margaret River area of Australia is known for the quality of its wines and yep, it’s on the western edge of the continent, flanking the Indian Ocean. And all these favored wine regions lay somewhere between latitudes 32 and 45, north and south.

In the northern coastal regions of California and Bordeaux, cold ocean currents descend southward. South of the equator, cold currents flow northward from the Antarctic along the coasts of Australia, South Africa, and Chile. In all these places, they cause an effect that allows the production of world class wines.

Let me explain.

The first time I visited coastal California, I was struck by the weather. The sky was a cloudless pure blue. The humidity was low and the air refreshing. The temperature was cool, in the upper 60s to low 70s, but the sunlight was incongruously warm on my skin. What a beautiful climate for people—and for grapevines, I thought. There’s an old saying that the places on earth most hospitable for human beings are also the most hospitable for wine grapes. California proves it to be true.

The California coastal climate provides great “sleeping weather” night after night. Because the ocean water descends from the Gulf of Alaska, and the ocean here is subject to upwelling that brings cold water to the surface, it’s cold along the northern California coast.

Westerly sea breezes provide natural summer air conditioning, with nighttime temperatures in the mid to upper 50s, so you always need a blanket, and the vines get to cool off and refresh themselves for another round of feeding and ripening the next day. During the winter, spring, and fall, frosts are rare on the hillsides and ridge tops, as cold air sinks away. This gives the elevated areas a very long, frost-free growing season. Budbreak for Pinot Noir and Chardonnay can occur as early as February and the grapes may not be harvested until September or, more rarely, even October. This long hang time allows for complete ripening, tame tannins, and mature flavors.

There’s another old saying among grape growers that vines like to see water—meaning that vineyards situated near a pond, a lake, or some body of water have an advantage. In cold winter regions, large bodies of water can ameliorate sub-freezing temperatures. Sunlight glinting off water can throw useful extra light up under grape leaves. And if vines can see water, that means they must be planted on an elevation of some sort, and that means good drainage—a soil characteristic that’s important if the fruit is going to reach its quality potential.

If vines like to see water, then the vines planted on the headlands and ridge tops along the Sonoma County coast have all the advantages in the world, because on clear days when the fog pulls out to sea, this is some of the most breathtaking scenery anywhere on earth, with oceanside hills that suddenly plunge a thousand feet or more down to the vast expanse of the Pacific Ocean rolling its whitecaps onto rocky outcroppings far below.

The Sonoma Coast is also a geological subduction zone, where the Pacific tectonic plate dives beneath the North American plate. The famous San Andreas fault runs along the Sonoma Coast. Land west of the fault was originally part of Asia, but over many eons it rode the deep movements of earth’s molten core across the Pacific, bumped into North America, and began to slide its way northward, tossing up steep, folded hills and mountains along its length. Thus the northern California coast is part of the Pacific Rim. As a consequence, soils along the Sonoma Coast are a hodge-podge of very well drained sandstone, igneous rock, decayed lava, metamorphic shales, calcareous seabeds, and gravelly, sandy loams. Each type of soil lends a unique quality to grapes grown in it. Grapes from these different soils can be blended to complement one another in a complex mixture. In addition, none of these soils are very deep or nutritious, which keeps vine vigor in check and berry size small—both requisites for top quality wine.

Put all these factors together and you have a unique area perfectly suited to produce world class wines whose grapes demand a long growing season with warm, even hot, summer days, and cool, even cold and foggy nights, to produce their finest expressions.

This rare but classic weather pattern is found in just a handful of places around the world, but grape growers and wine makers have identified them and are hard at work utilizing them.

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    Jeff Cox

    Jeff Cox
    Jeff Cox (B.A. Journalism, Lehigh University) has written three books and hundreds of magazine articles about wine for Decanter, The Wine News (where he was Contributing Editor), Men's Health, Diversion, Fine Wine Folio, and many other publications. Read More About Jeff