It was a decade in the works, but at long last on April 26, 2004, the “Oak Knoll District” was finally recognized as a distinct sub-appellation of Napa Valley. This 8,300 acre viticultural area (with 3,500 acres under vine) is located toward the southern end of the Napa Valley at a relatively low elevation on the valley floor, making it accessible to the climate-moderating effects of San Pablo Bay. Cooling breezes and coastal fog slow ripening, extending a growing season which can last up to eight months. Oak Knoll’s cooler climate is what distinguishes it from other Napa appellations. The Carneros appellation, located to Oak Knoll’s immediate south, is generally the only place in Napa that can claim a cooler climate. Enthusiastic advocates of the new AVA argue that Oak Knoll strikes the perfect climatic balance, not too warm and not too cool; what petition leader Trefethen Vineyards has coined the “sweet spot”.

In these conditions, a wide range of red and white varieties ripen with the perfect balance of sugar and acid. The area’s reputation for a delicate and restrained style of Chardonnay has notable wineries from neighboring appellations, including Chateau Montelena and Stag’s Leap Cellars, choosing Oak Knoll fruit for their Chardonnays. Perhaps more impressive is that even Riesling has found a terroir niche in this part of Napa. At the other end of the spectrum, the region is located just upland enough to produce some of the Valley’s best reds from Bordeaux varietals. A dozen wineries make their home within the newly delineated viticultural area, but at least another thirty regularly source grapes from Oak Knoll AVA vineyards. Starting with the 2004 vintage, consumers can expect to see "Oak Knoll District of Napa Valley" appearing on wine labels, and begin their discovery of the distinct characteristics of this new appellation.