American Viticultural Area labeling helps tell a story of a region and guide wine trade and enthusiasts in understanding growing
conditions and potential expectations of a specific region. The 11 viticultural areas of Paso Robles demonstrate the diversity of
Paso Robles Wine Country and provide information to consumers and trade about what is in the bottle, helping them make a
better-informed buying decision.
Paso Robles was the largest un-subdivided AVA in California at approximately 614,000 acres. By contrast, the Napa Valley ap-
pellation (which includes sixteen AVA's delineated within its bounds) is roughly one-third the area at 225,000 acres. Since the
Paso Robles AVA was established in 1983, Paso Robles has grown to encompass 200+ wineries and 40,000 vineyard acres. This
vineyard acreage is spread over a sprawling district roughly 42 miles east to west and 32 miles north to south. Average rainfall
varies from more than 30 inches a year in extreme western sections to less than 10 inches in areas farther east. Elevations range
from 700 feet to more than 2400 feet. Soils differ dramatically in different parts of the AVA, from the highly calcareous hills out
near us to sand, loam and alluvial soils in the Estrella River basin. The warmest parts of the AVA accumulate roughly 20% more
heat (measured by growing degree days) than the coolest; the average year-to-date degree days in the Templeton Gap since
1997 is 2498, while in Shandon far out east it's 2956. This difference in temperatures is enough to make the cooler parts of the
AVA a Winkler Region II in the commonly used scale of heat summation developed at UC Davis, while the warmest sections are
a Winkler Region IV.
