There are many factors which make Napa Valley special, in this entry we will touch briefly on three main characteristics: Climate (weather conditions), aspect (angle relative to the sun) and geology (soil content).
Because of the unique way that Napa is located and shaped, it has several microclimates which exist inside of it. Temperatures range from the cool and often foggy southern areas like the Carneros District, to the much warmer, closed-off northern regions where the Calistoga and St Helena Appelations are. Mountains and footbills protect much of the valley from excessive wind and rain, keeping the grapes safe from being torn apart or drowned. Napa also has a long growing season with warm, sunny days and cool nights- an ideal combination for allowing grapes to ripen slowly and evenly.
Vines are mostly planted on the valley floor, but more and more are being cultivated on the slopes. The wooded western slopes provide cool, afternoon shade- conditions which favour white grapes- Chardonnay, Sauvignon/Chenin Blanc, Riesling, whereas the more arid, rain-shadowed eastern slopes favour red varietals- Cabernet Sauvignon, Merlot, Pinot Noir and Zinfandel.
This beautiful balance of hot sun, cool ocean breezes, and (in some areas) shade provide enough sun and heat to ripen the thicker-skinned grapes (Cabernet, Zinfandel) but not overcook the more delicate varietals like Pinot Noir.
The soil content varies from one appellation to another, but the entire valley was once part of the ocean floor that has since been lifted up over years of tectonic evolution. The northern areas have been torn open and blasted with volcanic ash and rock, leaving a soil content of volcanic ash and gravel loams. The southern area closest to the San Pablo Bay has constantly been flooded and dried out over several centuries, depositing layers of sediment on the floor each time- leaving behind fertile clay and silt loams once the ocean retreats back.
Many 'Old World' French and Italian wines pride themselves on their 'terroir'- or the taste of the earth. Flavours of chalk, loam, gravel, slate etc come through first on these Old World wines, however California wines are initially very fruit-forward. Warm sun and [relatively] young vines give you powerfully ripe reds- flavours of black plums, cherries, cassis and berries will come before any earthiness or minerality.
So how do you choose the right Napa wine? There are hundreds upon hundreds of producers in the 16 appellations of Napa Valley (2012), you can easily drive yourself crazy picking apart which sub-regions have which micro-climate and soil ideal for growing which grape varietal in what year. My advice? Don't be afraid to try something new, and if you find something you really like then note it down (varietal, region, producer, vintage) and eventually you may begin to see a pattern.
Here is a fine example of a Napa Valley Cabernet: 2007 Esca Vineyards Cabernet Sauvignon- Calistoga, Napa Valley. It is not the boldest Napa Cab that I've had, especially for a 2007, but it does have a great, velvety smooth texture and nice round fruit flavours of black plums, currants and a little bit of vanilla and spice from the French oak barrels. Great wine to pair with anything from lamb shanks to swordfish.
At Wine Lab Camp- Costa Mesa, CA.
