Calistoga AVA is one of Napa Valley’s newer appellations, having been given appellation status in 2010. It is notable for its volcanic soil, which is unusual in the Napa Valley. Calistoga also experiences the greatest average 24-hour temperature swing of any Napa Valley AVAs, which Calistoga grape growers insist give the grapes time to “cool down” at night, making for better balanced wines. The 1,500 Calistoga vineyard acres are planted to Cabernet Sauvignon, Zinfandel, Syrah and Petite Sirah, along with smaller amounts of other varietals. Calistoga is at the northern end of Napa Valley, northwest of the Diamond District and St. Helena AVAs. Longtime winemaker Bo Barrett of Chateau Montelena, which is located in the Calistoga AVA, proposed the creation of the appellation.