California's winegrowing season started the other day. I had to put on a jacket. It felt like a bucket of cold water down the back of my neck. As a friend said through chattering teeth, "Somebody just opened the icebox door."
It might seem odd that a blast of frigid air would herald the opening of fruit-growing season, but that's what makes California distinctive.
The day certainly didn't start out in the refrigerator. Just before sunset we had arrived at a high ridge near the coast in western Sonoma County. We'd brought along grilled pork sandwiches and a bottle of Russian River Valley Pinot Noir, built a small fire and settled in to watch the immense full moon drift up out of the redwoods in dead-calm air, turning from orange to blazing white as it cleared the lowland haze over distant Santa Rosa.
It was T-shirt and shorts weather. We lounged comfortably in wildflowers and grass that still had weeks of green left before it would turn brown for the summer. The campfire smoke curled lazily straight up to the stars.
The wine was the '99 Dehlinger "Goldridge" Pinot Noir. It was perfect for the evening, a gracefully exuberant Pinot with piercing red berry and rose scents and bold red and black fruit flavor. Its clear flavors and bracing acidity spoke of vines rooted in Gold Ridge soil, the light sandy loam found primarily in the cool Green Valley appellation near Sebastopol, in the southern Russian River Valley.
The botanist Luther Burbank established a farm in Sebastopol because he felt this soil was a magical medium for growing luscious fruit, especially apples. This Pinot corroborated that vision. But more than that, it spoke of a special grape-growing climate--not just in the Russian River Valley but in all of coastal California.
Winemakers take a lot of credit for creating fine wines. Growers do, too, with considerably more justification. But it's really the Pacific Ocean that makes California's wines outstanding.
California is blessed with a cold coastwise current. Frigid to begin with, it also causes an upwelling of even colder water from great depths. In combination with onshore winds, these currents have a significant cooling effect on vineyards in coastal wine districts which otherwise would be much hotter.
Without the ocean's influence, California would be too hot for grapes such as Pinot Noir, Chardonnay and Cabernet Sauvignon. Extremely ripe fruit produces heavy, lackluster wines. The ocean's cooling effect allows the grapes to ripen fully without losing the precious acidity that creates intensity and fine structure. It emulates the effects of altitude and distance from the equator. In viticultural terms, vineyards near the coast seem to be at a higher latitude than the map would indicate.
Here's how it works: The northern and southern extremities of California's Central Valley (with its two great lobes, the Sacramento and the San Joaquin) reach very high temperatures during the summer because of the way the terrain concentrates solar radiation. As the hot air rises, it creates a vacuum that sucks cold marine air inland via the San Francisco Bay/Sacramento River system, the Russian River Valley and other gaps in the coastal mountain ranges south to Santa Barbara County.
The cool air typically flows inland during the afternoon, and it's often accompanied by fog that lingers until dissipated by the sun next morning. In the height of summer, the marine incursion is often large enough to cool the Central Valley significantly. As for the coastal valleys, the fog may cover them well into the afternoon for days on end, until enough heat accumulates inland to drive it offshore again. At that point the Central Valley begins super-heating again, and the cycle is repeated.
From the grape's perspective, the pace of sugar accumulation and physiological ripening in the latter part of the season are influenced by the way these fog events affect photosynthesis. Thus the character of a vintage is marked by the rhythm of marine incursions.
This regular five- to seven-day cycle is perhaps best understood using an organic model: Looking at a topographical map, you can visualize California as a living, breathing organism, with the Sacramento and San Joaquin valleys operating as a pair of lungs, the Golden Gate and San Francisco Bay as a mouth and the delta as trachea, and Lodi somewhere around the tonsils. The ongoing respiration, as the Central Valley inhales and exhales throughout the growing season, is what makes California wine grapes so good. The situation is similar to the southern Mediterranean coast of France--in fact, Lodi could be called the Languedoc of California.