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 California vineyards that thought they were planted with Durif/Petite Sirah were found to be field blends that contain some plantings of Peloursin. In addition to being a parent of Durif, Peloursin was also crossed with Persan to create Joubertin. DNA testing also suggest a relationship between Peloursin and Bia blanc which share some morphological similarities but the exact nature of that relationship is not yet known. Plantings of Peloursin are often confused with its offspring Durif and this was particularly the case in California where many plantings of Petite Sirah/Durif were discovered to actually be Peloursin. In the Jura region,