The Sonoma Coast appellation is the largest licensed American Viticultural Area (AVA) in the United States covering more than 200,000 hectares of land. In other words, it is enormous. To give you an idea of how enormous, Rioja has just over 60,000 hectares under vine. Naturally this makes drawing generalised conclusions about site specificity for the region pretty much impossible.
As a result, smaller unofficial designations are starting to gain traction – describing regions that have some contiguous factors and, leaving winemaking styles to one side, are likely to imbue the final wines with a recognisable sense of place. One such, is the “True Sonoma Coast”, used to describe the vineyards that “actually lie along the coast of Sonoma County!” As Andy Peay goes on, “This means that the afternoon breeze that comes in every day around noon cools vineyards unobstructed by higher western coastal ridges keeping top temperatures out of the 90s and, for those in the cool inversion layer below 1,000 feet, out of the 80s. The breezes and cool weather also often inhibit fruit set and a consequence of farming on the coast is that the yields are about half of what you can get inland.
This “true” Sonoma Coast can be further divided into three regions: the northern region around the town of Annapolis off Sea Ranch; the central region with the oldest vineyards on the coast now referred to by some as Fort Ross/Seaview Road; and the southern region near the town of Occidental. Peay Vineyards was a pioneer in the far northern section. We are discovering, however, that a critical factor for both vineyards in the northern and for those in the southern Sonoma Coast, is our elevation.
Our vineyard lies at 650-825 feet in elevation. Normally, temperatures fall by 1°F for every 400 foot gain in elevation. Along the Pacific Coast, this phenomenon is inverted as a layer of cold air ‹the inversion layer‹ is produced by a warm, less dense air mass moving towards the coast over the cooler, denser air caused by oceanic upwelling along the coast. This layer is maintained throughout the day and the breezes off the coast act as a fan blowing cold air along unobstructed land laying from sea level to 1,000 feet in elevation. Above this height, as in the central Sonoma Coast, and further inland, the normal relationship between temperature and elevation apply and it is hotter. Vineyards in this inversion layer are much cooler and as a result we achieve the Holy Grail in terms of high quality grape growing: cool sunlight.”