Found in the northern portion of Sonoma County, Russian River Valley is the coolest of Sonoma's AVAs because of its constant cover from clouds and Pacific fogs. The fog often swoops in during the early evening and causes many areas of the region to drop 35°F to 40°F from their daytime temperatures. This cooler atmosphere provides optimum growing conditions for Pinot Noir and Chardonnay. Other varietals found here are Zinfandel, Cabernet Sauvignon, Merlot, Sauvignon Blanc, Pinot Gris and Syrah. Also of note, Russian River winegrowers are currently demanding an expansion of the current AVA boundary, which currently includes the Chalk Hill and Green Valley AVAs.