Alexander Valley is one of the key winegrowing areas in California's Sonoma County. It is one of the warmer parts of Sonoma, with vineyards stretching from the edges of the Russian river up into the foothills of the Mayacamas mountains. Alexander Valley's key grape variety is Cabernet Sauvignon, making vibrant, fruit driven wines that are less earthy than their Napa counterparts.

The AVA covers the land along a 20-mile (33-km) stretch of the Russian river between the Mendocino County border and the city of Healdsburg. South of Healdsburg, where the fog-influenced climate is much cooler, the Russian River Valley AVA takes over, while Dry Creek Valley lies across the hills to the west. The separate but overlapping Pine Mountain-Cloverdale Peak AVA lies at the northern end of Alexander Valley.

The majority of Alexander Valley's vineyards are on the benchlands on the eastern side of the river, where the southwesterly aspect and alluvial gravel soils provide an excellent terroir for Cabernet Sauvignon. The valley is warmer than other parts of Sonoma due to its inland location, although cool winds and fog still make their way up the Russian river from the Pacific ocean via the Petaluma Gap. During the growing season, the days are warm and dry, with vineyards angled perfectly toward the afternoon sun. The nights are cooled by the wind and fog, which slows ripening and ensures the grapes retain acidity as they develop sugars and varietal character.