St. Helena AVA is at the northern end of Napa Valley just north of Rutherford and south of Calistoga. It is a relatively warm climate thanks to the Mayacamas Mountains on its western edge, which protect it from Pacific Ocean fog. Out of the 9,000 acres in the appellation, some 1,500 are under vine. The principal grapes grown in St. Helena are the Bordeaux grapes of Cabernet Sauvignon, Cabernet Franc and Merlot. St. Helena is considered prime wine producing territory, and it was one of the first important wine producing regions in northern California. The legendary Charles Krug founded his winery just north of the town of St. Helena in 1873, and today the appellation is home to many prestigious producers, including Abreu, Grace Family and Spottswoode.