Sonoma County AVAs

Sonoma County has within it 17 sub-region AVAs from different portions of Sonoma County, and also one additional AVA that is shared with Napa County. These sub-region AVAs are grouped into two main areas: Sonoma Valley AVA and Northern Sonoma AVA. In addition, there are a few independent sub-region AVAs in the Petaluma, Fountaingrove and Pine Mountain areas.

Bennett Valley AVA

Established as an AVA on 29 October, 2003.  The boundaries of this appellation lie completely within the North Coast AVA, almost completely within the Sonoma Valley AVA and overlaps into some areas of the Sonoma Coast AVA and Sonoma Mountain AVA.  The AVA is surrounded to the south, east and west by the Sonoma Mountains and to the north by the city of Santa Rosa.

The region receives a moderating effect on its climate from Pacific Ocean through the cool coastal fogs and breeze that creep into the area from the southwest through Crane Canyon between Sonoma Mountain and Taylor Mountain.

The Bennett Valley AVA is one of Sonoma County's newest AVAs and is a principal grape supplier to Kendall-Jackson.

Barbera, Cabernet Sauvignon, Cabernet Franc, Chardonnay, Grenache, Merlot, Pinot Noir, Sauvignon Blanc and Syrah are the leading grape varieties planted in the region.

Sonoma Mountain AVA

The Sonoma Mountain AVA, was established as an AVA on 22 January, 1985 and is located in the Sonoma Mountains, includes the town of Glen Ellen and is bordered on the west by the Sonoma Valley AVA.

The area is known for the diverse micro-climates that occur within the crevices and folds of the hillside terrain and as such is home to production for a wide range of varietals including Cabernet Sauvignon, Chardonnay, Pinot noir, Sauvignon Blanc, Semillon, and Zinfandel.

Los Carneros AVA

Los Carneros AVA (also known as Carneros AVA) received its AVA status on 17 August, 1983. The Carneros area was the first wine region in California to be defined by its climate characteristics rather than its political boundaries. Los Carneros AVA includes parts of both Sonoma and Napa counties. It is located north of San Pablo Bay.

The proximity to the cool fog and breezes from the bay makes the climate in Los Carneros AVA cooler and more moderate than the wine regions farther north in Napa Valley and Sonoma Valley. The cooler climate has made Los Carneros attractive for the cultivation of cooler climate varietals like Pinot Noir and Chardonnay. Many of the grapes grown in Los Carneros are used for sparkling wine production.

The Carneros region covers 58,000 acres located along the low-lying hills of the Mayacamas range as it descends underneath San Francisco Bay. Elevations of most vineyards range from 400 feet in the foothills to near sea level closer to the bay. The official boundaries of the AVA fall into both Napa and Sonoma counties with the largest portion being in Sonoma and entitled to use the Sonoma Valley AVA designation as well. The Napa portion of Los Carneros is similarly entitled to use the Napa Valley AVA designation. The region is moderately cool and windy with marked influences from nearby San Pablo Bay, making it the coolest and windiest AVA in both Napa & Sonoma. Early morning fog is a persistent feature.

The soils of the Carneros region are predominantly clay and very thin and shallow (approximately 3 feet deep), providing poor drainage and fertility. The fierce and persistent winds coming off the bay encourages the grapevines to struggle and retain moisture. While this aids in keeping crop yields small, it can also delay the grapes from ripening sufficiently. In vintages with a long, drawn out growing season that allow the grapes to ripen, intense and vivid flavors can develop.

Moon Mountain District Sonoma County AVA

Established as an AVA on 1 October, 2013.  The Moon Mountain District Sonoma County AVA is within the Sonoma Valley AVA and North Coast AVA areas, just north of the city of Sonoma. This mountainous region on the very eastern edge of Sonoma County has a historic reputation for producing rich, intensely-flavored wines from Cabernet Sauvignon and Syrah varietals since the 1880s. 

The District covers 17,663 acres of land stretching north-south along the western slopes of the Mayacamas mountains between Sugarloaf Ridge State Park and Los Carneros viticultural area with the Napa Valley’s Mount Veeder viticultural area outlining the eastern slopes. Its name is derived from Moon Mountain Road, which traverses through the area and itself a reference to Sonoma, which means 'valley of the moon' in the local Native American dialect. A clear view to San Francisco 50 miles south is not uncommon from Moon Mountain District vineyards.

The distinguishing features of Moon Mountain District are its topography, geology, climate, and soils. It lies in one of the warmer parts of Sonoma County due to its inland location. At elevations ranging from 400 to 2,200 feet above sea level, vines grow in a variety of soils, mainly rocky and of volcanic origin, on the western slopes and ridge tops of the Mayacamas Mountains.

Crosswinds from both the Pacific Ocean to the west and San Pablo Bay in the south bring cooling maritime influences to the vineyards, but by the time the winds have travelled across the valley floor they have warmed considerably. Most of the region's vineyards face southwest, subjecting them to stronger afternoon sunlight. The higher elevation vineyards places their varietals above the influence of the famous Sonoma fog. The warmer climate gives Moon Mountain District a longer growing season than other parts of Sonoma Valley, with earlier budburst in the spring and a longer hang time for the grapes in the autumn. Cold air tends to drain off the hillside vineyards into the valley, reducing the risk of damaging frosts and allowing for a long, slow maturation period. As a result, Moon Mountain District grapes have a good balance of sugars and acidity, leading to well-balanced wines.

The region's iron-rich volcanic soils are quite distinct from the sedimentary soils of the surrounding area. These red, rocky soils are thin, well-drained and therefore highly suited to viticulture. Louis M. Martini's famed Monte Rosso vineyard, a 120-year-old vineyard within the appellation, is named for these red soils.

Moon Mountain contains 11 wineries and 40 commercially-producing vineyards that cultivate approximately 1,500 acres well-established throughout the mountainous area around the hills and ridges.

Alexander Valley AVA

Established as an AVA on 23 October, 1984.  The Alexander Valley AVA is one of the most densely planted of all of Sonoma County's AVAs. Located along the Russian River, the boundary of this appellation extends north of Healdsburg up to Mendocino County north of Cloverdale. Highway 101 runs through the valley, and the Russian River flows down the valley, surrounded by vineyards on both sides. From the higher elevations of the valley rim, there is a view as far south as Taylor Mountain and Sonoma Mountain. The region was named for Cyrus Alexander, owner of a part of the Rancho Sotoyome Mexican land grant, in 1847. 

The Alexander Valley area is sheltered from the influence of the nearby Pacific Oceans by the low-lying hills northeast of Healdsburg. The dominant vineyard soil of the region is alluvial. During the day, the Alexander Valley is one of the warmest areas in Northern California but at night experiences a wide diurnal temperature variation that offers cool climate conditions. The region's proximity to the Russian River serves a source for early morning fog that covers the lower vineyard areas until it is burned off by the morning sun. 

Viticulture has existed in the area since the 1850s but the wine industry has only fairly recently experienced success, beginning in the 1960s.  The profile of Alexander Valley wines has historically centered around the approachability and richness of the wines with Cabernet Sauvignon being noted for characteristic chocolate notes and warm mouthfeel. After Cabernet, Chardonnay is one of the leading varietal plantings followed by Sauvignon Blanc and Zinfandel.

A characteristic associated with Alexander Valley wines is a rich, fleshy mouthfeel and a degree of voluptuousness due to the area's generally warm climate and ability to sufficiently ripen the grapes. While the wine exhibit a degree of drinkability and accessibility in their youth, they may not have the same aging potential as wines from Napa Valley or even other areas of Sonoma County. The Alexander Valley is capable of growing a wide range of grape varieties but in recent years, the area has been noted for the quality of its Cabernet Sauvignon and Merlot.

The alluvial soils of the region tend to impart a rich, chocolate note to the Cabernet. Other Alexander Valley varietals that have been gaining recognition include Chardonnay, Nebbiolo and Sangiovese. The Chardonnay from this region is characterized by its rich, tropical fruits. Some experts, such as Jancis Robinson, have speculated that Zinfandel and Sauvignon Blanc may eventually prove themselves to be best suited to the climate and soils of the Alexander Valley.

Chalk Hill AVA

Established as an AVA on 20 October, 1983.  The Chalk Hill AVA is a sub-appellation of the Russian River Valley located near the town of Windsor along the foothills at the southern end of Alexander Valley and along the Santa Rosa plain. The name Chalk Hill comes from the unique volcanic soil of chalky white ash which has shown itself to perform well with planting of white wine varietals like Chardonnay and Sauvignon Blanc. The majority of the region's wineries are located on the western slopes of the Mayacamas Mountains.

The Chalk Hill AVA is located in Sonoma County. The boundaries of the wine appellation cover the northeast corner of the Russian River Valley AVA. The majority of vineyards are located to the east of U.S. Route 101, near the town of Windsor. The name Chalk Hill comes from the unique volcanic soil of chalky white ash which has shown itself to perform well with planting of white wine varietals like Chardonnay and Sauvignon Blanc. The majority of the region's wineries are located on the western slopes of the Mayacamas Mountains.

The boundaries of the Chalk Hill AVA cover 33 square miles of land within the northeast corner of Russian River AVA. Many of the region's 1,600 acres of planted vineyard land is located along the western slopes of the Mayacamas Mountain reaching up to altitudes of 200–1300 feet. Compared to the rest of the Russian River Valley, the Chalk Hill region is relatively warm due to the influence of a thermal belt that runs through the area. Harvest time often takes place in September while harvest in the surrounding regions usually takes place in October.

The area takes its name from the "chalky" white soils of the region. However the soils themselves do not contain any chalk but rather are composed of a mixture of quartzite abundant volcanic ash, sand and silty loam. The volcanic was emitted into the area by Mount St. Helena over a course of centuries, creating vineyard soils that are not very fertile and are able to restrain vigor in the vines.

Dry Creek Valley AVA

Established as an AVA on 3 August, 1983.  The Dry Creek Valley AVA in the Russian River Valley centers around the Dry Creek, a tributary of the Russian River, and is approximately 16 miles long and 2 miles wide. The appellation is known particularly for its Sauvignon Blanc and Zinfandel production. 

The appellation benefits from the proximity of the Lake Sonoma reservoir for irrigation in this relatively dry area.

At the turn of the 20th century, Dry Creek Valley was one of California's most prominent producers of Zinfandel. During Prohibition, much of the valley was converted to plum, pear, and prune trees, and much of the fruit was processed by Sunsweet Growers in Healdsburg. Since the resurgence of wine grape production in the 1970s, Cabernet Sauvignon and Zinfandel have become the most planted varieties, and Dry Creek Valley AVA has become one of the state's top Zinfandel producers. Sauvignon Blanc has become the most important white grape varietal produced in the valley.

Over 50 wineries are resident in Dry Creek Valley AVA, and over 160 wineries produce wines that bear a Dry Creek Valley AVA designation. Dry Creek Valley AVA is home to the majority of the Sonoma vineyards of E & J Gallo Winery, who established winery facilities in the valley in the early 1990s.

Green Valley of Russian River Valley AVA

Originally established as an AVA on 20 November, 1983.  The Green Valley of Russian River Valley AVA was formerly known as the Sonoma County Green Valley AVA. 

Many wines that could have been labelled with the original Sonoma County Green Valley AVA designation were instead labelled with the broader appellation designation of the Russian River Valley AVA, due to the greater market awareness of Russian River Valley wines. Eventually, seeking to connect the region with the more commercially successful Russian River Valley name, the appellation formally changed its name around the date of April 23, 2007.

Located at the southwestern corner of the Russian River Valley AVA, its close proximity to the Pacific Ocean makes it one of the coolest appellations within Sonoma County. The climate in the Green Valley is even cooler than other parts of the Russian River Valley, and favors the cultivation of cool climate grape varietals like Pinot Noir, Chardonnay and Gewürztraminer.

Knights Valley AVA

Established as an AVA on 20 October, 1983. The Knights Valley AVA occupies the boundaries between the southern end of the Alexander Valley AVA and the northern end of Napa Valley. The easternmost designated Sonoma County wine region, Knights Valley AVA has the warmest climate in the county. The valley lies between the Alexander Valley AVA and Chalk Hill AVA wine regions to the west and the Mayacamas Mountains to the east. Geographically, the appellation separates the rest of Sonoma County from the Napa Valley AVA.

Knights Valley AVA is one of Sonoma County's original five AVAs. Knights Valley AVA includes approximately 37,000 acres. Over 30 growers maintain the 2,000 acres planted to wine grape vineyards. The area is known for its Cabernet Sauvignon.

Protected from direct Pacific Ocean influence, the valley is the warmest of Sonoma County's viticulture areas. Warm afternoons and cool evenings provide the ideal environment for growing Bordeaux grape varieties. Cabernet Sauvignon remains the star in the valley. Also present are the rest of the Meritage blend: Merlot, Cabernet Franc, Malbec, and Petit Verdot, as well as Sauvignon Blanc, Chardonnay, Viognier, Syrah, and some limited plantings of other varietals.

Rockpile AVA

Established as an AVA on 27 February, 2002.  The Rockpile AVA is situated at the northwest point of the Dry Creek Valley AVA, past Healdsburg. Rockpile AVA was Sonoma County's twelfth designated wine appellation. The wine region consists of approximately 15,400 acres in northwestern Sonoma County.

All of the AVA has an elevation in excess of 800 feet above sea level. Most recently eleven vineyards were listed as currently located within the AVA and at last reported count there were approximately 160 acres of planted wine grapes.

The area was first planted by Italian immigrants at the turn of the 20th century. Many of today's vineyards were formerly occupied by a reservoir created by the Warm Springs Dam on the Russian River. The area is known for its fruity, ripe Zinfandels.

Russian River Valley AVA

Established as an AVA on 20 October, 1983.  The Russian River Valley AVA lies adjacent to and west of the city of Santa Rosa and incorporates the southern reach of the Russian River, where the river bends westward and cuts through the Coast Range to the Pacific Ocean. Within the boundaries of the Russian River AVA are the sub-region AVAs of Chalk Hill AVA and Green Valley of Russian River Valley AVA. In 2003 the AVA was expanded to include 767 acres south of Fulton.  In 2005 the AVA was expanded again by 30,200 acres to 126,600 by recognizing previously overlooked portions of the fog regions.

With parts of the AVA located less than 10 miles from the Pacific, the climate of the Russian River AVA is characterized by cool morning fog that comes in from the ocean through the Petaluma Gap and burns off during the day. The cooling influence of the fog is responsible for the large diurnal temperature variation with nighttime temperatures dropping as much as 35 to 40 degrees Fahrenheit from daytime high. In the summertime, the warmth of the season is tempered by the maritime influence of fog that facilitates a long, slow ripening period and limits the risk of over ripeness or "baked" flavors in the grapes. Harvest in the Russian River Area often take place at later dates than in its neighboring regions. 

Portions of the appellation's soil consist of sandstone of loam known as "Goldridge soil". Some of the area's most respected Pinot noir and Chardonnay vineyards are planted along deposits of Goldridge soil. Near the town of Sebastopol, a different soil that is more clay based, known as "Sebastopol soil" has also shown itself to work well with Pinot noir due to its ability to retain less water than Goldridge soil. This soil was created by water flowing off the Sonoma Mountains that carried with it clay deposits. A third soil type, found close to the river, is predominantly alluvial and makes up the benchland regions of the river.

Presently the Russian River AVA includes more than 15,000 acres planted to wine grapes. At last count, 79 wineries were listed in the Russian River Valley Winegrowers website. The area is known for its success with cool climate varietals, notably Pinot noir and Chardonnay.  The appellation accounts for about one-sixth of the total planted vineyard acreage in Sonoma County.  According to the trade group Russian River Valley Winegrowers, 42 percent of the grapes harvested in the region are Chardonnay, while 29 percent are Pinot Noir. While the region is predominantly associated with Chardonnay and Pinot Noir, hillside vineyard locations have shown success with other varieties such as Syrah and Zinfandel. 

Over time the region began to develop a reputation for the quality of its Chardonnay and Pinot Noir for both still and sparkling wine production. In the late 1990s and early 21st century, as the popularity for Pinot Noir grew, the region saw an explosion of investment with Pinot plantings jumping from 4,000 acres to over 12,000 acres by 2003.

Despite its close proximity, the Russian River AVA produces Chardonnays that are dramatically different from those found in the Alexander Valley AVA. The region's cool climate produces more grapes with higher acidity that tend to be more balanced than the fatter, creamy style found in the Alexander Valley. Grapes from the Russian River and smaller Green Valley areas have been prized by sparkling wine producers for their crispness and high quality.

Older Pinot Noir clones planted in the mid to late 20th century, including the Martini, Swan, Pommard, and 115 clones, produced a "classic" style of Russian River Pinot Noirs that were characterized by vibrant (but pale) color, lively acidity, cherry and berry fruit flavors and delicate aroma that would often include earthy mushroom notes. While that style had it share of fans, the lack of coloring would be a factor in poor score wine ratings from wine critics.

Other winemakers adopted new trellising systems that allowed for more leaf removal which exposed the grapes to more sunlight. In addition to enhancing some of the color producing phenols, the new trellising also served to increase sugar content (and subsequently alcohol levels) and decrease the amount of the green tasting pyrazine compounds found in the grapes. The style of Pinot Noir produced from these techniques tend to be heavier, more fuller bodied and almost "Syrah-like".

Sonoma Coast AVA

Established as an AVA on 10 June, 1987.  The Sonoma Coast AVA contains more than 500,000 acres, mostly along the coastline of the Pacific Ocean. It extends from San Pablo Bay to the border with Mendocino County.  The area has such a broad range of microclimates that petitions have been made for the creation of sub-AVAs such as the Fort Ross-Seaview AVA which was approved in December 2011.

The appellation is known for its cool climate and high rainfall relative to other parts of Sonoma County. Pinot Noir grapes grow especially well in this region, where they benefit from slightly cooler day temperatures.

The following seven cities are located in, or partly in, the Sonoma Coast AVA:  Cotati; portions of Healdsburg; Rohnert Park; Petaluma; portions of Santa Rosa; Sebastopol; portions of Sonoma; The Petaluma Gap is also part of the Sonoma Coast AVA.

Fort Ross-Seaview AVA

Established as an AVA on 13 December, 2011.  The 27,500-acre Fort Ross-Seaview AVA is located in the western part of Sonoma County in the coastal hills above Fort Ross State Historic Park, overlooking the Pacific Ocean. Carved out of the larger Sonoma Coast AVA in 2011, the 27,500-acre Fort Ross-Seaview AVA was given special consideration for its soaring elevation and remote, rugged location.  It lies entirely within the Sonoma Coast AVA and does not overlap other AVAs.

To understand Fort Ross-Seaview, picture a vineyard on the crown of a coastal ridge, surrounded by a sea of fog. Although the AVA is located just a few miles from cold Pacific Ocean waters, between Jenner and The Sea Ranch, it is also significantly defined by its higher elevation. In the summer, vineyards bask in warm sunlight indeed, while many are above the damp belt of fog that invades the Petaluma Gap and Russian River Valley. Fort Ross-Seaview is an essentially chilly climate on the edge of grape-growing possibility, yet, at times, may receive more sunlight than areas like Green Valley of the Russian River Valley, which is defined by immersion in fog. 

Sonoma County's first wine grapes were planted in 1817 at the fur-trading Russian-American Company's outpost at Fort Ross. The area's modern viticultural history didn't begin until 1973.  For the time being, Pinot Noir and Chardonnay are undeniably the most popular grapes in Fort-Ross Seaview, but a surprise runner-up is the South African red variety Pinotage.

Vineyards within this area are generally located on rounded ridges with summits extending above 1,200 feet consisting of steep, mountainous terrain made up of canyons, narrow valleys, ridges, and 800- to 1,800-foot peaks.  At last count the appellation contained 18 commercial vineyards on 506 acres. 

Precious few of its wineries are open to the public, but its 500 vineyard acres produce some of Sonoma County's most sought-after Pinot Noir and Chardonnay. 

West Sonoma Coast AVA

Established as an AVA on 22 May, 2022.  West Sonoma Coast was the 19th AVA in Sonoma County. The AVA is located on the furthest western sliver of Sonoma County encompassing the steep, rugged mountainous terrain along the Pacific Ocean coastline. The AVA comprises three sub regions from north to south: Annapolis, the Fort Ross-Seaview AVA and Freestone-Occidental. The Pacific Ocean forms the western boundary of the AVA, and the shared Sonoma-Mendocino County line forms the northern boundary. The eastern boundary follows a series of elevation contours within 5 to 7 miles of the Pacific Ocean while the southern boundary is marked by the northern boundary of the Petaluma Gap AVA.

Elevation of the West Sonoma Coast AVA ranges from 400 to 1,800 feet with vineyards planted on steep ridge tops along the San Andreas fault line up against the consistently cold Pacific Ocean, both above and below the fog line. As a result, temperatures are at least 10 or more degrees cooler than the rest of the Sonoma Coast AVA. Due to the immediate proximity of the Pacific Ocean, cold marine air and heavy fog create challenging conditions for grape growers, while offering distinct advantages for wine grapes. The maritime conditions moderate the temperature in the vineyards – daytime highs are cooler, while nighttime lows are warmer than just a few miles inland. This modest diurnal temperature swing allows the fruit to ripen slowly throughout the day and the night, a phenomenon experienced only in a truly cold-climate, maritime environment. This slow, steady ripening promotes the development of fruit that reaches true physiological maturity at lower sugar levels with pronounced acidity.

Located on the furthest western sliver of Sonoma County, made up of steep, rugged mountainous terrain along the Pacific Ocean coastline, the West Sonoma Coast AVA holds approximately 50 vineyards planted with several varieties, mostly Pinot Noir, Chardonnay, and Syrah. The approval of the AVA recognized the uniquely cold, marginal, and maritime growing conditions of this region.

The climatic characteristics of West Sonoma Coast guide the style of the wine produced in the AVA. Bright acidity, moderate alcohol, and pure flavors are the qualities that are often associated with the wines from the West Sonoma Coast. The status of the region as an AVA provides clarity for the consumer who can expect a wine labeled ‘West Sonoma Coast’ to have these defining qualities that differentiate its wines from those grown on warmer sites farther inland in the Sonoma Coast AVA.

The area comprising the West Sonoma Coast AVA has a long agricultural history dating back to the 1880s, with the earliest vines planted as early as 1817. In addition to wine grapes, the area still produces commercial apples and supports a lively dairy and ranching industry, as well as many nature parks, conservancy efforts and environmental projects.

Fountaingrove District AVA

Established on 17 February, 2015, the Fountaingrove District AVA encompasses 38,000 acres in the eastern boundaries of Sonoma County.  Tucked into central-eastern Sonoma County, the Fountaingrove District AVA is surrounded by the Russian River Valley AVA, Knights Valley AVA, Sonoma Valley AVA, and Napa Valley sub-appellations including the Spring Mountain District AVA.

The Fountaingrove District AVA is often seen as a sleeper of an appellation within Sonoma County, achieving American Viticultural Area (AVA) status without much fanfare or controversy.  Taking its name from an historic area of northeastern Santa Rosa, the Fountaingrove District.

Viticulturally, it also fills the gap — classified as Warm Region II in the Winkler heat summation scale, it's more marine-influenced than Alexander Valley AVA and areas of northern Napa Valley, but warmer than the Russian River Valley AVA. The terrain is mainly rolling hills, with soils derived from Sonoma Volcanic and Franciscan Formation bedrock.

The appellation is home to over 600 acres of hillside vineyards with elevations reaching up to 2,000 feet. The region is best known for its Cabernet Sauvignon, Merlot and Syrah varietals.  Historically, Zinfandel, Riesling, Pinot Noir, and many other grapes were grown in the hills of the Fountaingrove area. Overall today, Cabernet Sauvignon, Chardonnay, Sauvignon Blanc, Merlot, Cabernet Franc, Zinfandel, Syrah, and Viognier are the most common varietals being grown.

Petaluma Gap AVA

Established as an AVA on 6 December, 2017.  The Petaluma Gap AVA is an area which spans 202,476 acres stretching through an 30 miles inland valley from the Pacific coast at Bodega Bay southeast to Highway 37 at Sears Point on San Pablo Bay straddling the border of northern Marin and southern Sonoma counties. The AVA lies entirely within the North Coast AVA and partially in the Sonoma Coast AVA.

The Marin County portion of the Petaluma Gap remained outside of the Sonoma Coast AVA, while the Sonoma County portion remained within the Sonoma Coast AVA. TTB allowed the partial overlap to remain, primarily because the name “Sonoma Coast” is associated only with the coastal region of Sonoma County and does not extend into Marin County.

The distinguishing features of the Petaluma Gap are topography and climate. Its topography sets the AVA uniquely from Sonoma Coast AVA. The ‘Gap’ literally describes the geological valley that is a 15 miles wide by 30 miles corridor between the coastal hills allowing the salty maritime winds and a cycle of morning fog, clearing sunny spells, more fog in the afternoon and clearer evenings to flow eastward through the region. A typical day in the valley can experience a temperature change of 40 to 50 °F.

These cycles contribute to a longer growing season benefiting cool-climate grape varieties. The lower elevations and rolling hills in Petaluma Gap allows the marine air to enter at a higher velocity than the surrounding regions where higher and steeper slopes disrupt the air flow. Although marine breezes are present during most of the day, the wind increases significantly in the afternoon hours because the rising inland hot air pulls the cooler, heavier marine layer from the coast causing a steady airflow.

The effect of these prolonged high winds on the grapes is a reduction in photosynthesis to the extent that the grapes have to remain on the vine longer (hang time) in order to reach a given sugar level, compared to the same grape varietal grown in a less windy locations. Grapes grown in windy regions are typically smaller and have thicker skins than the same varietal grown elsewhere. The smaller grape size, thicker skins, and longer hang time concentrate the flavor compounds in the fruit, allowing grapes that are harvested at lower sugar levels to still have the typical flavor characteristics of the grape varietal. Also with the wind, there is no botrytis or mildew issues and the grapes have a higher skin-to-juice ratio. 

Around 75 percent of plantings are Pinot Noir, with Chardonnay at 13 percent, and Syrah 12 percent.

Pine Mountain-Cloverdale Peak AVA

Established as an AVA on 26 October, 2011.  The Pine Mountain-Cloverdale Peak AVA is in Sonoma County and also in Mendocino County. It is located at the top of Pine Mountain, at the Northern end of the Mayacamas Range, which separates the Napa and Sonoma growing regions. The AVA, is one of the highest grape growing regions in California, which rises from 1,600 feet at its lowest point to 3,000 feet at the mountain’s peak, has grapes growing primarily at 1,800 feet and higher.

The very high elevation of the mountain affects fog cover, hours of daylight, daytime and nighttime temperatures, rainfall, and wind — virtually every climatic element influencing wine grape production.

On average, there is a twelve degree drop in temperature between the valley floor and the center of the Pine Mountain-Cloverdale Peak AVA. Despite the cooler days, growers on the mountain paradoxically experience relatively warmer night time temperatures, the result of cooler air dropping into the valley, displacing warm air upwards. At 1600 feet, the valley also sits well above the fog that collects in the mornings and evenings down in the valley, giving it three to four more hours of sunlight a day. This unique microclimate creates an altered growing season for Pine Mountain growers, with bud break occurring two to three weeks after vineyards on the valley floor.

The Pine Mountain-Cloverdale Peak Appellation has rocky volcanic soils of steep hillsides and ancient alluvial fans. Soils are shallow to moderately deep fractured shale and sandstone, very well drained through gravels. In general, soils are less than 3 feet deep, with over 50% at 12 inches or less.  The mountain is home to a number of natural springs, which were bottled and sold as a mineral water for over 50 years. Pine Mountain Spring water ceased production in the 1950s.

The Pine Mountain-Cloverdale Peak AVA is one of the highest and most remote winegrowing sub-regions in Sonoma County. Of its 4,600 acres, just 230 acres are planted with grapevines.  The long season and high sunlight exposure here favor red wine grapes; Cabernet Sauvignon is the undisputed sovereign of the mountain, accounting for some 80 percent of vineyard acres, while Merlot and Malbec are a distant second and third. Alternative red varieties include Sangiovese and Lagrein, and the occasional white variety, such as Muscat or Riesling, is grown here, too.