Carneros straddles the borders of the Napa and Sonoma Valleys on the north coast of San Pablo Bay. This appellation has thin soils and receives little rainfall. As the sun heats up the vineyards and mountainsides of Napa Valley to the north, the rising hot air draws cool air and fog over Carneros from the bay. Carneros extends to the base of the Mayacamas hills, with plantings from almost sea-level up to several hundred feet. The weather pattern and low altitude moderate vineyard temperatures, providing just the right conditions for growing cool-climate varietals with crisp acidity and moderate sugar levels.
The region's unusual microclimate has attracted Carneros wine makers who sought to produce superb New World Pinot Noir. The region's best producers have earned a reputation for their crisp, structured Pinots that showcase spicy, dark-berry aromatics and flavors. In addition to its Pinot Noir, Carneros is also known for its crisp, citrusy Chardonnays and bright sparkling Carneros wines.
Sonoma Valley is nestled between the Sonoma Mountain Range on the west and the Mayacamas Mountains on the East. North Coast winemaking began here back in 1825 when the missionary fathers established Mission Sonoma. By the 1850s, Sonoma had evolved into California's wine making center, a distinction it gradually ceded to Napa over the next fifty years. In the 1970s, however, Sonoma wines had begun to reclaim the international renown they enjoy today.
With more than 7,000 acres planted to Sonoma Valley wine grapes, the Valley stretches for 40 miles north from the San Pablo Bay to just below Santa Rosa. Although summertime fog enters the valley from both the north and south, Sonoma's cooler regions by far are located in the southern part of the valley, primarily in the Carneros district. In contrast, the climate along the valley floor in the middle of the region can be quite warm.
Though compact, Sonoma Valley hosts a very wide array of vineyard soil types, topographies, and elevations. That said, there are a few rules of thumb: In the southern Valley (between Carneros and the town of Sonoma), the best Sonoma wines come from early-maturing varieties like Chardonnay, Gewurztraminer, Pinot Noir, and, from some producers, Merlot. On the hillsides and along the hilltops, Cabernet Sauvignon and Zinfandel fare the best so long as the elevation is above the frost line. Chardonnay and Pinot Noir, the two most widely cultivated varieties in Sonoma, perform best along the benchlands between Sonoma and Kenwood.
It is remarkable that an industry essentially less than a half-century old could capture the attention of the American wine-buying public to the degree that California has. Powerful consumer interest in California wine is driven by two major factors. The more obvious reason is that California's best wines, which come from grapes grown in a benign climate featuring endless sunshine, very warm summer days, and generally dry harvests, and wonderfully fruity, full, and satisfying, and rarely too austere or tannic to be enjoyed from day one.
California is blessed with an extraordinary range of soils and microclimates, allowing for the successful cultivation of many varieties. In at least three out of four years, the best sites produce healthy, ripe fruits that are the envy of European producers in more marginal climates. The other reason Americans buy so much California wine is that California is the home team. Clearly, a high percentage of domestic wine drinkers are more comfortable buying American wines (and not just wines of California) than imports. Then, too, foreign bottles are generally identified by place name, rather than by the more familiar varieties that American wine drinkers have come to know and enjoy.
Moreover, in much of North America, outside the top 15 or 20 largest metropolitan markets, consumers have limited access to imported wines even if they wanted to buy them.
For many, Napa Valley is California wine, and Cabernet is king in Napa Valley. Meanwhile, the Burgundy varieties Chardonnay and Pinot Noir have gravitated to cooler areas, generally closer to the Pacific, such as the western stretches of Sonoma County, the Anderson Valley in Mendocino County, and the Santa Maria and Santa Ynez valleys within Santa Barbara County. Syrah vines have yielded interesting wines in a range of styles all over the state, in regions as disparate as Mendocino County, the Sonoma coast, Carneros, Paso Robles, and Santa Maria Valley. Very good Zinfandel similarly comes from multiple growing areas, although to date the age-of-vines variable has been almost as important as geography. Zinfandel, though its roots are in Europe, is a true California original and the only California wine imitated abroad. It's also a variety of which there are still significant plantings of very old vines, in some cases dating back to the end of the 19th century.