For many years, the grape growers and winemakers on the western Mayacamas range wished they had a way to differentiate themselves from those in the lower elevations of Sonoma Valley.
In October of 2013, they got their wish when the Moon Mountain District Sonoma County (that is its full given name) was granted American Viticultural Area status.
Part of the larger North Coast AVA, the Moon Mountain District’s distinct features bring into closer focus the vast diversity within the Sonoma Valley AVA.
Sharing the ridge of the Mayacamas, the Napa/ Sonoma County line defines much of the eastern boundary of Moon Mountain District. The city of Sonoma is the demarcation to the south, Sugarloaf Ridge marks the northern line, and Valley of the Moon is the western boundary of the AVA.
The moderately steep slopes rise from 400 feet to 2,200 feet at the highest peak, distinguishing the region from the flatter terrain of the valley below. The high elevations allow for cool mountain air to drain off into the valley, reducing frost in the mountains at critical times in the growing season, as well as placing a vast portion of the region above the cooling marine fog.
Despite being tempered by two coastal influences — the ocean and San Pablo Bay — the region stays warmer due to the higher elevations.
Soils are dominated by Sonoma Volcanics — lava flows of ryholite, andesitic and basaltic that over time formed the rocky soils important for good drainage. The thin, loamy soils of the area result in vines with less vigorous growth and lower yields, but fruit with greater concentration of flavors.
You don’t see the Moon Mountain District Sonoma County designation on very many labels just yet, but that’s likely to change in the future as wines currently in barrels get transferred to bottles.