Sonoma County is not an AVA, but it is a commonly used informal designation for wines made outside of more specific AVAs within Sonoma, which is a large wine producing region just west of Napa Valley. Though Sonoma is often overshadowed by its glamorous neighbor Napa Valley, it has a long history of wine production. The area specialized in jug wine until the mid-20th century, when Sonoma producers took a cue from Napa and started improving quality. Unlike Napa, where Cabernet Sauvignon is king, Sonoma specialized in Chardonnay, Pinot Noir and Zinfandel, though excellent Cabs are produced too. There are at present 16 AVAs within Sonoma County, and, like much of the West Coast of the United States, new AVAs are created in Sonoma County with regularity. Some Sonoma appellations, such as the Russian River Valley, are renowned for Pinot Noir and Chardonnay.
Despite its popularity, this grape is quite rare. Less than 10,000 acres are planted worldwide, with the bulk in California. In France, the grape is referred to as Durif. Not to be confused with Syrah, Petite Sirah is a cross of Syrah and Peloursin. The result is darker and fuller.