Livermore Valley AVA unique east-west orientation, unlike many other winegrowing valleys. Due to a reliable onshore afternoon/evening breeze off of the San Francisco Bay a wide fluctuation in temperature between sites and a large diurnal temperature swing occur. Livermore Valley is considered a Winkler Region III grape growing zone with temperatures comparable to northern Napa Valley appellations such as St. Helena or Calistoga. The relatively obscure Petite Sirah grape produced Livermore's best historically known red wine, although the climate also makes for interesting dessert wines as well as excellent Cabernet Sauvignon, Merlot and Rhone varieties. The original plantings of Sémillon and Sauvignon blanc
Peloursin Rif" (later Durif) by ampelographer Victor Pulliat in 1868. Durif later made its way to California where it was eventually named Petite Sirah. In the late 20th century University of California, Davis researchers led by Dr. Carole Meredith discovered that some of the California plantings of Petite Sirah were, in fact Peloursin, and that Peloursin had a parent-offspring relationship with Durif that likely sprung from a crossing with Syrah. Peloursin is a vigorous grapevine capable of producing high yields and excessive foliage if not kept in check with winter pruning and summertime leaf pulling. The variety tends to be a