Granted official AVA status in 1981, Sonoma Valley boasts some four-thousand-five-hundred vineyard hectares and more than eighty wineries. The diversity of the valley’s topography and geology, and its subsequent impact on growing conditions has led to the establishment of a number of notable sub-appellations distinguished by their unique terroir. These AVAs can choose to market their wines under the wider Sonoma Valley label if they so wish. Occupying the southern part of the county, the climate of Sonoma Valley is influenced by its sheltered position between two mountain ranges as well as by the cool fog and marine air that sweep inland off San Pablo Bay. Southerly vineyards, such as those in the [Carneros](/ava/carneros-ava) sub-appellation, experience a distinctly cool climate on account of their proximity to the ocean, and subsequently enjoy an extended growing season resulting in well-balanced, deeply concentrated fruit. Non-surprisingly these areas are famous for their premium varietals from [Chardonnay](/chardonnay) and [Pinot Noir](/pinot-noir), as well as traditional method sparkling wines from the same grapes. Further north however, as the effect of the ocean diminishes with distance, vineyards occupy elevated sites on wooded hillsides. These vines - including notable plots in the [Bennett Valley](/ava/bennett-valley-ava), [Moon Mountain](/ava/moon-mountain-ava) and [Sonoma Mountain](/ava/sonoma-mountain-ava) AVAs - bask in the [Californian](/region/california) sunshine and benefit from significant diurnal temperature variation, with altitude induced cooler evenings tempering the daytime warmth. In these conditions, [Cabernet Sauvignon](/cabernet-sauvignon) grapes thrive, delivering rich and appealing expressions with deep colour and silky tannins. An area of rustic charm and abundant natural beauty, Sonoma Valley is often heralded as the birthplace of [Sonoma’s](/county/sonoma-county) commercial wine industry with a history of viticulture dating back to the middle of the nineteenth century. Today, that focus remains, with many of the appellation's wineries opening up tasting rooms and offering vineyard tours to the public. Amongst the best known producers here is the [Buena Vista Winery](/producer/buena-vista-winery) - which is widely thought to be [California’s](/region/california) first commercial cellar.