Guenoc Valley was approved as an appellation on December 21, 1981. It was the first time an AVA designation was granted to an area with just a single winery. Originally made famous by Victorian actress Lilly Langtry, who planted vines here in the 1800s, Guenoc is a small inland valley of about 23,000 acres, extending from upper Napa County well into Lake County. The appellation is defined by the rocky ridge surrounding it and the Magoon Family Vineyards (simply labeled Guenoc) sit at 400 feet. These vineyards are the first in the area to be harvested, as extremely hot days are common and over-ripening is a concern. Luckily, the area also has very cool nights, preserving acidity and producing rich wines with elegant structure. There are now 340 acres of vines surrounding the Guenoc Estate. The winery works with Semillon, Sauvignon Blanc and Chardonnay, as well as Malbec and Petite Syrah from the estate vineyards.