The character of any wine comes from the grapes that go into it, and the character of those grapes is firmly rooted in the place where they are grown. Napa Valley's rich heritage and reputation are a testament to this, as the renowned winegrowing region enjoys the best of all scenarios for fine grapes, superb wines and great diversity of style.
America's Premier Wine-growing Appellation...
Although the most renowned in the United States, the Napa Valley Appellation is also one of the smallest yet most diverse winegrowing regions in the world. Only 4% of wine produced in California is from the Napa Valley Appellation even though 8% of the state's vineyards are found here. This is because the grape clusters are thinned to allow only the very best to come to fruition, resulting in harvesting at less than half the statewide average. Yields of Cabernet Sauvignon from Napa Valley Appellation are generally 1 ½ to 4 tons per acre.
Located approximately 60 miles (100km) north of San Francisco, Napa Valley is bounded to the west by the Mayacamas Mountains and to the east by the Vaca Range. The Appellation stretches 40 miles in a northwesterly direction, starting with the windswept flats and gentle hills of Carneros in the southern end-which is near sea level-and rising quickly above the Valley floor to Mount St. Helena at 4,339 feet (1,323 meter) at the head of the Valley.
The Napa Valley Appellation, which is one-eighth the size of Bordeaux, is planted to approximately 45,000 acres (18,210 hectares) of wine grapes, covering a mere 9% of the Appellation's 485,000 total acres.
Napa Valley Rocks: The Napa Valley Appellation Education Program
The Valley was formed not only by tectonic plate movement and volcanic action, but also by alluvial runoff and the flooding of San Pablo Bay, which at one time reached as far north as the town of Yountville. Rocky knolls and alluvial fans interrupt the level expanses of the Valley floor, each evidence of the geologic occurrences of the past. The area's topography supports over 100 variations of soil, ranging from well-drained gravelly soil to moisture-retaining clay. These soils vary in depth and fertility, and the composition greatly affects the wine grapes. Generally, soils found on the Napa River flood plain and the Valley floor are deeper than the rocky soils covering the slopes and hills.
Napa Valley also enjoys a Mediterranean climate - which covers only 2% of the earth's surface and features a long growing season marked by sunny, warm days followed by cool evenings - an idea combination for allowing grapes to ripen slowly and evenly. The most moderate temperatures are found in the Carneros region, which is cooled by marine breezes that sweep through the Golden Gate and across San Pablo Bay. Farther up Valley, the Pacific Ocean exerts less influence: temperatures are warmer in the summer and cooler in the winter and rainfall is greater. On any given day the temperature difference between Carneros and Calistoga is as much as the temperature difference between the Atlantic and Mediterranean regions of France.
The configuration of hills, cooling effects of the Pacific Ocean, exposure and elevation all work to create distinct microclimates within the Napa Valley Appellation, each imprinting recognizable characteristics on the grapes grown within it. Each of these regions is designated an American Viticultural Area (AVA). The Napa Valley itself is an AVA, with 14 sub-AVAs existing within its boundaries. This offers growers a spectrum of viticultural possibilities, winemakers a diverse palette to create from and consumers an array of quintessentially classic wines.