Chalk Hill AVA

Chalk Hill AVA sits northeast of the Russian River Valley, approximately 8 miles north of Santa Rosa near the town of Windsor. As a sub-appellation of Russian River Valley, it occupies a distinct thermal position, sitting higher and warmer than the valley floor below. The AVA covers 21,120 total acres, of which roughly 1,600 acres are under active vine cultivation. Five wineries account for over 1,400 of those vineyard acres.

• Sub-appellation of Russian River Valley AVA, within Sonoma County
• Located northeast of the Russian River Valley, near Windsor
• 21,120 total acres; 1,600 cultivated vineyard acres
• Named for a prominent hill blanketed in distinctive white volcanic ash

The defining feature of Chalk Hill is its volcanic ash soils. Mount Saint Helena deposited a layer of chalky white tuff across the area, creating a quartzite-rich, low-fertility substrate that drains well and ranges from sandy to silt loam with embedded volcanic debris. This mineral-rich but nutrient-poor profile naturally restricts vine vigor and limits yields to around 2-3 tons per acre, concentrating flavor in the fruit that remains.

• White volcanic tuff (ash) soils from Mount Saint Helena eruptions
• Quartzite-rich, low-fertility, well-draining sandy to silt loam
• Low fertility drives naturally restricted yields of 2-3 tons per acre
• Soil composition directly responsible for the region's minerality signature

Chalk Hill occupies a warmer microclimate than the surrounding Russian River Valley, classified in the Region I-II heat summation range (2,010-3,000 degree days). Marine influence tempers daytime temperatures through moderate ocean breezes, while thermal belts at mid-elevation protect vineyards from spring frost damage. Fog, common throughout Sonoma, tends to escape to lower elevations rather than lingering in the AVA. The growing season runs approximately 242 days, with average annual precipitation of 36 inches falling primarily between November and March. Harvest typically concludes by the end of September, earlier than neighboring valleys.

• Region I-II heat summation classification (2,010-3,000 degree days)
• Thermal belts at mid-elevation prevent spring frost damage
• Fog drains to lower elevations, leaving Chalk Hill warmer and sunnier
• 242-day growing season; harvest complete by end of September

Chardonnay is the signature variety of Chalk Hill, celebrated for its mineral-driven character shaped by the volcanic ash soils. Sauvignon Blanc also performs exceptionally here, alongside Semillon. Warmer sites within the AVA support Bordeaux varietals including Cabernet Sauvignon, Merlot, Cabernet Franc, Petit Verdot, and Malbec. Syrah, Zinfandel, Sangiovese, and Pinot Noir round out the planted varieties. Chalk Hill Estate has been a pioneer in Chardonnay clonal research, developing the proprietary Chalk Hill Clone 97.

• Chardonnay is the flagship variety, producing mineral-driven, complex whites
• Sauvignon Blanc and Semillon thrive alongside Chardonnay
• Bordeaux varietals dominate warmer sites within the AVA
• Chalk Hill Clone 97 is a proprietary Chardonnay clone developed within the AVA

Sonoma County viticulture traces back to Mission San Francisco de Solano in 1824, with cultivation in the Windsor area documented from 1855. Chalk Hill Estate was founded in 1972, and Rodney Strong Vineyards pioneered Chalk Hill Chardonnay labeling as early as 1977. Rodney Strong subsequently spearheaded the push for official AVA recognition, which was granted on October 21, 1983. The designation was later amended in 1988. Chalk Hill became the 49th AVA in the United States, the 32nd in California, and the 4th in Sonoma County.

• Chalk Hill Estate founded 1972; Rodney Strong began Chalk Hill Chardonnay labeling in 1977
• AVA established October 21, 1983; amended 1988
• 49th AVA in the United States; 32nd in California; 4th in Sonoma County
• Rodney Strong Vineyards spearheaded the official AVA petition