High Valley AVA

High Valley AVA sits within Lake County on the eastern side of Clear Lake in Northern California. The valley runs 9 miles long and 3 miles wide on an unusual east-west axis, a configuration caused by the volcanic activity of Round Mountain, a dormant cinder cone. This transverse orientation distinguishes it as one of only two such AVAs in California. The surrounding ridges reach 2,200 to 2,400 feet, with the valley floor settled between 1,700 and 1,800 feet.

• Located within the broader Lake County AVA in Northern California
• East-west valley orientation is rare, caused by volcanic activity of Round Mountain
• Valley floor elevation of 1,700 to 1,800 feet; ridgelines reach 2,200 to 2,400 feet
• Situated on the eastern side of Clear Lake

High Valley is the coolest of all Lake County AVAs, a distinction driven by persistent marine breezes channeled off Clear Lake and Snow Mountain. Daytime summer temperatures climb high enough to ripen warm-climate varieties, but evenings cool dramatically, producing diurnal temperature shifts of approximately 50°F during July and August. This extreme day-to-night variation extends the ripening window, allowing grapes to develop concentration while retaining the acidity that defines the appellation's character. Plant hardiness zones range from 8b to 9b.

• Coolest AVA in Lake County due to Clear Lake marine breezes and Snow Mountain winds
• 50°F diurnal temperature shift in July and August prolongs ripening
• Cool nights preserve natural acidity alongside full fruit development
• Plant hardiness zone 8b to 9b

High Valley's soils reflect its volcanic and alluvial origins. The southeastern portion of the appellation contains Maymen, Hopland, and Mayacama Series soils, while the western hills carry Millsholm, Bressa, Hopland, Estel, and Maymen Series soils. Upper slopes feature shallow deposits of sand, gravel, and tephra with strong volcanic characteristics that stress the vines and reduce yields. The valley floor is carpeted in alluvial soils that support the white grape varieties and produce wines with a distinct character from the hillside reds.

• Southeast soils: Maymen, Hopland, and Mayacama Series
• Western hills: Millsholm, Bressa, Hopland, Estel, and Maymen Series
• Upper slopes contain volcanic tephra, shallow sand, and gravel
• Valley floor alluvial soils suit white varieties such as Sauvignon Blanc

Petite Sirah and Syrah lead among red varieties, joined by Grenache, Zinfandel, Cabernet Sauvignon, Merlot, and Pinot Noir. Sauvignon Blanc and Muscat represent the white plantings. The combination of lower yields, volcanic hillside soils, and dramatic diurnal swings produces dark, supple red wines with higher intensity and concentration than neighboring appellations. Whites from the cooler valley floor show bright acidity and complex aromatics. Grapes from High Valley have historically fetched approximately 30% more than other Lake County fruit.

• Petite Sirah and Syrah are leading red varieties alongside Zinfandel and Grenache
• Sauvignon Blanc and Muscat cover white grape plantings
• Lower-than-average yields produce wines of higher intensity and concentration
• High Valley grapes historically command a 30% premium over other Lake County fruit

High Valley's viticultural roots stretch back to the Pomo Indian descendants, the Elam and Kamdots tribes, who first settled the land. Commercial viticulture took hold in the late 1800s, and around 1875, the Ogulin family planted Zinfandel and Muscat vines brought from Slovenia; some of these remain among California's oldest surviving vines. Lake County was one of California's largest wine-producing areas before Prohibition ended production. The region was eventually re-established as a formal AVA on July 1, 2005.

• First settled by Pomo Indian descendants of the Elam and Kamdots tribes
• Ogulin family planted Slovenian Zinfandel and Muscat vines around 1875
• Pre-Prohibition Lake County ranked among California's largest wine-producing areas
• High Valley AVA formally established July 1, 2005