The vineyards of Calistoga AVA occupy sites at elevations between one-hundred and four-hundred metres above sea level. They enjoy excellent exposure to sunshine, significant rainfall relative to other [Napa Valley](/ava/napa-valley-ava) appellations and the most extreme variations in temperature between day and night. The combined influence of these factors leads to the production of rich, concentrated fruit which retains its natural acidity, and subsequent well-balanced wines. Whilst the topography of the area is notably diverse, Calistoga’s geology is somewhat more uniform; free draining volcanic soils - rocky on the hillsides, silty / clay on the valley floor - prevail across the entire appellation which enables growers to control vine quality and improve consistency within the vineyard. Although it has been producing grapes and wine for more than one-hundred-and-fifty years, Calistoga was only officially recognised as an AVA in 2010, after around seven years of debate between opposing parties. Whilst some of the appellation’s winemakers championed the distinction of the area on account of is unique terroir and microclimate, others opposed the formation of a separate zone in disagreement that wines produced under the label must contain no less than 85% of grapes within its bounds. Calistoga Cellars and Calistoga Estate were perhaps the most serious opponents whilst [Chateau Montelena](/producer/chateau-montelena-winery) - famous for the prize winning Chardonnay at The Judgement of Paris - was its most fervent supporter. When Calistoga AVA was finally approved, all wineries were informed that they must comply with the 85% rule by the 2013 vintage. Today Calistoga has just over three-hundred hectares planted to vine and almost forty wineries. Red grapes [Cabernet Sauvignon](/cabernet-sauvignon) and [Zinfandel](/zinfandel) dominate, supported by smaller quantities of [Merlot](/merlot), [Syrah](/syrah) and [Petite Sirah](/petite-sirah). White varieties - [Chardonnay](/chardonnay) and [Sauvignon Blanc](/sauvignon-blanc) - account for only a tiny fraction of production but have a serious reputation for quality highlighted by the afore-mentioned [Chateau Montelena](/producer/chateau-montelena-winery) varietal. The winemakers of Calistoga are often considered an eccentric bunch whose unique land area and equally singular approach to their craft continues or deliver some of the valley’s most delectable wines.