Napa Valley, an hour's drive north of San Francisco, California, is the most famous and prestigious wine region anywhere in the New World. Although a number of grape varieties are grown in the valley's vineyards, the area is particularly known for its Cabernet Sauvignon. The classic 'Napa Cab', the archetypal Napa Valley wine, is a rich, oak-aged red with aromas of blackcurrant, boysenberry, liquorice, vanilla and smoky, bittersweet chocolate.
Situated immediately north of San Pablo Bay, the valley runs roughly SE - NW for approximately 35 miles (57km) between the Vacas and Mayacamas mountain ranges (to the east and west respectively). The scenic 40-minute drive between the Napa and Calistoga townships passes through some of the most valuable viticultural real estate on Earth.
There are several reasons for Napa Valley's global renown as a wine region. Most obvious is that the wines are produced to high standards, in a popular style, and are very well marketed. Then there is the region's accessibility from San Francisco city. This draws millions of wine tourists to the valley each year to sample its wines and world-class gastronomy. And no less important (even after almost four decades) is the triumph of Napa Valley wines over their rivals from Bordeaux and Burgundy in the 1976 Paris Judgment.
Wine has been made in Napa Valley since the 19th century, but it is only since the 1960s that wine of any particular quality has been produced. The founding pioneers of Napa Valley winemaking were George C Yount (see Yountville), and John Patchett and his winemaker Charles Krug, founder of the eponymous winery. Also of note are the Beringer brothers Jacob and Frederick, whose Beringer Vineyards (est. 1875) is one of California's oldest continuously operated wineries and features on the the U.S. National Register of Historic Places.
The range of grape varieties grown in the Napa Valley has evolved steadily over the 150 years since Yount planted his first vines. Cabernet Sauvignon has risen confidently to become Napa's star performer, and is the most widely planted grape in almost all of the valley's sub-regions. The notable exception to this rule is Carneros, whose cool, breezy mesoclimate is better suited to Pinot Noir and Chardonnay. Merlot is also prominent, although since its fall from favor in the 1990s it is now used mostly as a blending component for Napa's Meritage wines and Bordeaux blends. Although it represents only a small proportion of the valley's vineyard area here, Zinfandel remains significant in the Napa wine portfolio. Hillside sites above the valley floor provide exactly the kind of warm, dry environment in which Zinfandel (California's signature variety) performs best, particularly on rocky, free-draining slopes.
White wines are strongly outnumbered here, but play a valuable supporting role, bringing an element of diversity to the valley. Once upon a time, Riesling was the variety of choice, but has now been replaced almost completely by Sauvignon Blanc and Chardonnay.
Climate, geology and topography are three essential components in what makes Napa Valley such a first-rate viticultural area. The combined influences of San Pablo Bay and the hills of the North Coast Ranges are responsible for the valley's very particular mesoclimate. The bay generates morning fog, and the hills channel it inland, up into the valley. Without this fog that comes rolling in from the bays, the valley's climate would be substantially warmer than it is, making it difficult to achieve structure and balance in the wines. The fog doesn't reach the higher parts of the valley, however, leaving these to rely on the cooling effects of altitude to keep their vines in balance.
The Napa Vintners video below explains a little more about the Napa Valley terroir.