Yolo County is the northernmost wine region within California's vast Central Valley. The county is home to a significant agricultural industry of which viticulture is only a small part; this is prime tomato country. That said, the county boasts four sub-AVAs as well as the most famous oenological college in the state, at the University of California, Davis. Chardonnay, Chenin Blanc and Petite Sirah are the most important wines produced in the region.
Yolo County is in the middle of a cluster of famous Californian wine zones. Napa County is just over the Vaca mountains to the west of Yolo and Lake County is in the north-west. Solano County shares its northern border with Yolo, and the Lodi AVA is in the south-east.
The four sub-AVAs here are spread out across the county. The Capay Valley and Dunnigan Hills AVAs are in the north-western corner, while Clarksburg and Merritt Island are along the edge of the Sacramento River, which forms the eastern border of the county.
It is up this river that marine influences creep, and Yolo County is slightly cooler than most of the other AVAs within the Central Valley. This is particularly true in Clarksburg and Merritt Island, where fog and coastal winds cool the vineyards daily, extending the growing season. However, the fertile, poorly drained soils here are more conducive to high yields than high quality, making these two AVAs excellent for the bulk production of cool-climate-style wines.
Dunnigan Hills and Capay Valley in the west are better suited to producing quality wines. Higher altitude means a more-pronounced diurnal temperature variation, and careful site selection optimises sunlight and wind exposure for any given vineyard. Capay Valley's soils are rocky and volcanic, similar to those in nearby Lake County, and the dry, loamy Dunnigan Hills soils offer excellent drainage, leading to lower yields of grapes with an excellent concentration of flavor.
Yolo County (then named Fremont) was one of California's original 18 counties, and was formed in 1850. As in much of the state, winemaking came to the region during the California Gold Rush of the 1850s, and was all but abandoned during the era of Prohibition in the 1920s. There is some debate as to the origins of the word Yolo, although the consensus is that it is Native American in origin. Popular culture has offered up an alternative meaning for the word that has been happily adopted by the county: YOLO is an anagram for 'You Only Live Once.'
