North America


  • California is responsible for 94% of the wine produced in the United States, and wine is produced throughout the state. California, like other wine producing areas in the U.S., is divided into smaller regions known as AVAs, or American Viticultural Areas.

    The most prestigious AVA in the state is Napa Valley. The Napa Valley begins at sea level about 30 miles from San Pablo Bay, where the maritime influence is very important, and stretches to Calistoga, with an elevation of 350 ft. It is bordered by hills on either side, Spring Mountain and Mount Veeder on the west and Howell Mountain and Atlas Peak to the east.

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  • Soil
    The soils of the Napa Valley floor derive from an ancient seabed, while the hills on either side were formed by volcanic activity. Over the ages erosion washed stones down from these mountains, resulting in gravel beds or alluvial fans being deposited along the edge of the valley, and the formation of clay beds at the mouth of the valley. These alluvial fans improve drainage and are sometimes called "benchland."

    Climate – Mountain vs. Valley
    The essential dichotomy in the Napa Valley is between the vineyards on the valley floor and those on the surrounding hills, which can be very different, with cooler temperatures in the mountain vineyards due to the higher elevation.

    During the day, the sun heats the air on the valley floor, but when the sun sets, this warm air rises, displacing the cooler air further up the slopes, which then sinks to the valley floor, an effect known as heat inversion. Heat inversion produces more constant average temperatures, an advantage for ripening grapes which produces wine with good structure and tannic grip.

    Mountain vineyards also produce very healthy grapes because breezes that flow through the vineyards reduce the chance of rot. Rainfall can be heavy at low to medium elevations, but above the fog line sunny days are prevalent and rainfall is lower than normal.

    A third factor is the thin soils that are typical on mountain vineyards. These soils are able to hold just barely enough water. This hydric stress on the vines limits vigor and helps produce grapes with concentration and structure.

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  • Mt. Veeder
    Mt. Veeder is a hillside AVA located along the southwest border of Napa Valley at elevations up to 2,600 feet. 1,000 acres of steep mountain vineyards are planted out of a possible 15,000.

    Cabernet Sauvignon and Chardonnay dominate the grape varieties planted along with small quantities of other grapes. The reds tend to have good tannic structure, but can be less generous than those produced on Howell Mountain.

    Spring Mountain
    Up the valley from Mount Veeder lies the Spring Mountain AVA, with 1,000 acres planted on Spring Mountain out of a possible 8,600 situated at 400-2,600 feet elevation. The best sites are located above the fog line, giving sunny conditions that advance ripening. This elevation is slightly lower than Mt. Veeder to the south or Diamond Mountain to the north, and this helps pull cool air in from the Pacific Ocean which moderates the heat and helps even ripening.

    The vineyard sites are also very steep, making them difficult to work, and yields can be low. This helps improve the concentration and structure of the fruit, an effect intensified by the region's relatively cool climate and thin soils.

    Spring Mountain's vineyards are planted mainly to Bordeaux varietals and Zinfandel, with Chardonnay, Sauvignon Blanc and Riesling for white grapes. Newton is one of the most well known of the quality producers, and their site is among the finest for Bordeaux varietals.

    Diamond Mountain
    Diamond Mountain, located at the northwest end of Napa valley, is recognized as a quality region, but was only declared a separate AVA in 2001. The soils are very rocky, and only 500 acres out of a possible 5,000 are planted. These hillside vineyards are planted at relatively high elevations on largely volcanic soils and are among the best in Napa Valley.

    Howell Mountain
    The first delimited AVA, Howell Mountain has vineyards planted at elevations of 1,400-2,200 feet. Only 600 acres out of a possible 14,000 are planted. Many vineyards here face west or north, and the soil is mostly volcanic in origin, well drained and fairly thin, producing low yields and limiting vigor. Black grapes such as Cabernet Sauvignon and Zinfandel are in the majority, and the wines can be big, tannic, and dark. Chardonnays grown here can be lean and austere.

    Atlas Peak
    Southeast of Howell Mountain and east of Stag's Leap is Atlas Peak. High altitiude, cool vineyards exposed to the west receive the late afternoon sun, helping ripen grapes effectively. Volcanic soils help limit vigor, but are difficult to work. 1,500 acres out of a possible 11,000 in the AVA are planted.

    Wild Horse Valley
    South of Atlas Peak and east of Carneros is the Wild Horse Valley AVA, this is a small appellation, with only 100 acres planted out of a possible 3300 acres. This is a dry area of high elevation vineyards with volcanic soils on the border with Solano county.

    Stag's Leap
    Stag's Leap is an AVA on the eastern edge of the valley floor, where half of the delimited two square miles are planted to vines in loam, clay and volcanic soils. Half of the available area is planted to vines.

    The AVA consists of what some have described as a "valley within a valley," a free-standing hill up against the alluvial fans deposited by the slope wash from the Vaca mountains on the eastern side of Napa Valley. On top of this alluvial matter lies a fairly rich, loamy clay soil that gives the wines a lush softness.

    It is cooler than the regions to the north because of cool nights; the average rating is as a Region II, giving the fruit a longer hang time than other valley floor AVAs. Cabernet and Merlot dominate the vineyards, and produce wines with a supple black cherry/cassis fruit.

    West of Stag's Leap is the 8,000-acre AVA of Yountville, with half of this area under vine. This is one of the oldest regions in Napa since the historic Rancho Caymus was first planted in 1836. In spite of this, the AVA was approved only in 1999. This area still receives some maritime influence from the bay. The soils are rich and can promote vigor.

    Oak Knoll
    Oak Knoll is the region just to the south of Yountville and north of the city of Napa. 3,500 acres are planted out of a possible 8,300. Although Yountville was given AVA status in 1999, Oak Knoll was not granted the same distinction until April, 2004. It has fairly deep, fertile soils and a relatively cool climate.

    On the other side of Yountville lays Oakville, a very well known AVA of 5,700 acres. To-Kalon and Martha's Vineyard are among the most famous sites. 5,000 acres are planted on deep loamy soils over gravel that assists drainage. The area produces grapes with a rich berry fruit and a characteristic minty character. Oakville is best known for Cabernet, but some Chardonnay and Sauvignon Blanc are grown as well.

    Just north of Oakville is Rutherford, again planted on gravelly loam over alluvial fans from the Mayacamas mountains to the west and the Vaca range to the east. This area is warmer than Oakville and produces softer, fatter wines. André Tchelistcheff was the first to comment on the earthy flavor he referred to as "Rutherford Dust," giving the wines aromatic depth.

    St. Helena
    North of Rutherford lays St. Helena AVA. The soils are varied here, with well-drained benchland on the western edge near the hills and sandy loam in the center.

    The climate is much warmer than in the districts to the south since there is little cooling influence from the ocean. This means that the wines tend to be very ripe and silky with supple tannins and soft acidity.

    Calistoga is at the northern end of Napa. It is not a recognized AVA by the government, but the wines from here display a very distinctive ripeness and grip. This far north in the valley, the sun is hot, but the elevation moderates temperatures. The soils are rocky and gravelly, fairly deep and have low vigor and produce moderate yields.

    Pope Valley & Chiles Valley
    There are several areas outside of the main part of Napa Valley that are still entitled to use the name. The Pope Valley is northeast of Howell Mountain. Neither an AVA nor really in Napa, it is included with Napa for historical reasons. It is characterized by hot days and cold nights and produces fairly soft wines. The Chiles Valley is an AVA of 1,000 acres planted with a hot climate, cut off from the moderating influence of the sea.

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