California’s Napa Valley wine region is located immediately north of San Pablo Bay, in the north-eastern corner of the San Francisco Bay Area. Formed by the Napa river as it flows between the Vacas Mountains (to the east) and the Mayacamas (to the west), the valley runs roughly north-west to south-east for approximately 35 miles (57km). The scenic 40-minute drive between Napa and Calistoga passes through some of the most valuable viticultural real estate on Earth.
The Napa Valley, or simply Napa, is one of the world's most famous wine regions, unchallenged by any region in the Americas or indeed the New World. There are several reasons for this global renown, one being the ease with which Napa can be reached by visitors travelling from San Francisco city. Several million wine tourists pass through the valley each year to sample its wines and the world-class gastronomy that has developed alongside them. Napa’s triumph over Bordeaux and Burgundy in the 1976 Paris Judgment is unquestionably another factor, as it propelled the valley and its wines into the international spotlight. The remarkable endurance of Napa's fame is partly due to the persistently high quality of its wine, but also the number of wines labelled as Napa Valley, whether alone or in conjunction with a more location-specific AVA.
Wine has been made here 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 (after whom Yountville is named), and John Patchett and his winemaker Charles Krug, founder of the eponymous winery in St Helena. Napa is home to Beringer Vineyards, one of California's oldest continuously operated wineries. Established in 1875 by Jacob Beringer and his brother Frederick, the Beringer site has been added to the 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 to be Napa's star performer and signature variety. It is the most widely planted grape in almost all of the valley's sub-regions, with the notable exception of Carneros, where Pinot Noir and Chardonnay make the most of the cool, breezy mesoclimate. Merlot is also prominent here, although since its fall from favor in the 1990s it is now used mostly as a blending component for Napa's Bordeaux blend and Meritage wines.
Although it makes up a small proportion of plantings here, Zinfandel has a strong impact on the Napa wine portfolio. The hillside sites above the Napa Valley floor provide just the warm, dry environment that California's signature variety prefers, particularly when complemented by rocky, free-draining, infertile slopes. White wines are strongly outnumbered in Napa, but are nonetheless present. While Riesling was once the variety of choice, it has now been almost completely replaced by Sauvignon Blanc and Chardonnay.
Another key factor in Napa's phenomenal success as a wine region is its weather patterns. The hydrography of the wider Bay Area, plus the topography (specifically, the orientation) of the North Coast Ranges, are behind the unique Napa Valley mesoclimate: one creates fog, the other channels it inland. Without the fog that rolls in from the bays, the valley would be substantially warmer than it is, and its wines less structured and balanced. Furthermore, Napa's quality wine production would be limited to the cooler climes higher up in the hills, which would increase the cost of production and dramatically reduce the area suitable for viticulture. Without this mesoclimate, the Napa Valley would never have become the world-famous wine region it is today.