Napa Valley is one of the most famous vintner locations worldwide, despite producing only 4 percent of wine in California and 0.4 percent of the world’s supply. The favorable soil and weather conditions that mimic the Italian Mediterranean climate are advantageous for winemaking and have given the region widespread acclaim. In the earlier days of winemaking, the effect of soil and climate differences weren't well understood, with wineries growing different grape sorts side by side. However, the industry has advanced, with expanding knowledge and technological advancements in recent decades. The various soil types and climate conditions around Napa Valley have allowed local vineyards to showcase the particular benefits of specific locations within the valley for certain grape varieties. Napa Valley is considered an AVA (American Viticultural Area), gaining that status in 1981, but has 16 smaller AVAs nestled inside. The number of AVAs is evocative of the enormous potential this region has in delivering some of the best wines in the world. The southernmost AVA, Los Carneros, has primarily clay-based soil and is highly affected by the winds blowing inward from San Pablo Bay. With a cool temperature year-round, it specializes in Pinot Noir and Merlot wines. Coombsville and Wild Horse Valley are the furthest southeastern AVAs, with relatively low temperatures year-round. Both AVAs have primarily volcanic soil, which is incredibly fertile. Coombsville wineries specialize in Cabernet Sauvignon, Merlot, Chardonnay, Pinot Noir, and Syrah wines. Wild Horse Valley’s altitude and lack of water retention make it more demanding to grow grapes in, with Pinot Noir and Chardonnay specialties of this AVA.