[This photo is of a weather station at The Rubin Family of Wines, in Green Valley of the Russian River Valley. Fog is hanging in the background.]
Green Valley of Russian River Valley is comprised of the following small towns, which are all bordered to the west by the California Coast Ranges. Sebastopol is located in the southeastern portion of this region. Occidental is to the southwest; its redwood forest leads to the Ranges, and ultimately to the Pacific Ocean. Graton is central to the small valley, while Forestville is located in the northern part of this American Viticultural Area (AVA), which is also engulfed by Redwoods. Being surrounded by Redwoods, which leads to mountainous terrain, this Redwood forest tightly closes the western and northern region of Green Valley in Sonoma County, creating a small bowl.
All of these towns contribute to Green Valley’s very distinct terroir. Visually, on a map, Green Valley is well suited to being its own AVA, and so it was defined early on. At the time, it was simply Green Valley; but with a neighboring Green Valley in Solano County, in 2008, a push was successfully made to change the name from simply Green Valley to Green Valley of Russian River Valley… This action continues to set it apart.
From the Green Valley Website:
Green Valley became a federally recognized AVA in 1983. In 2008, the TTB approved a name change and the official name is now Green Valley of Russian River Valley. It is today renowned for producing exceptional cool climate wines.
An important part of any terroir is how the region gets its moisture. In Green Valley, there’s a geographical water source that plays a major role, called the Petaluma Wind Gap. The 12-mile waterway of the Petaluma River originates in the south of Green Valley in the town of Petaluma. It flows in a southerly direction and empties into the San Pablo Bay marshes, continuing southward to empty into San Francisco Bay. Fresh marine air usually blows eastward through the gap, and then branches into southerly and northerly streams. The Petaluma Gap affects wind patterns as it spreads to the north, creating microclimates and the pristine air quality found in Green Valley. As it flows northward, it brings winds and fog into Green Valley.
Because of its closeness to the gap, Green Valley usually experiences cooler mornings; and, for a longer period of time than the northern regions of Russian River Valley. Green Valley is the first place where the fog rolls in, and it’s the last place where it burns off. All of this creates one of the coolest and foggiest part of Russian River Valley… ideal for cool weather grape growing.
Other small waterways are subsidiaries, which is another reason the region holds the fog that comes into the area from the Petaluma Gap, just a bit longer, as early morning sun rays begin to evaporate the moisture that has come in during the early hours of the evening. The southwestern border has Graton’s tree lined Atascadero Creek which becomes the Green Valley Creek in Sebastopol. This is a tributary of the Russian River (to the northern part of Green Valley), and empties into the Pacific Ocean at Jenner, California.
In late afternoon, you can see the fog beginning to move inland, and the same holds true for some late afternoons.