The east-west orientation of the 152.3 square miles (97,483 acres) with a wide, open valley and rolling hills means cool winds and fog flow in freely from the Pacific Ocean, settling most noticeably in lower-lying areas.

The result is a mild Mediterranean climate that lengthens the growing season and contributes to the eventual sugar/acid balance in the grapes from Santa Maria Valley's 7,500 acres (3,000 ha) cultivated vineyards.

[8] The Santa Maria Valley geography channels dense banks of morning fog from the Pacific Ocean that takes many hours to burn off, only to be replaced by chilly afternoon breezes.

Along the northern portion of the Santa Maria-Sisquoc River colluvial soils cover slope sides giving rocky freshness to grapes grown throughout.

[12] Due to the cooler mesoclimates, the valley is renowned for producing some of California's finest Pinot Noir and Chardonnay wines.

[7] On January 28, 2011, the TTB granted a petition to expand the southern border of the Santa Maria Valley American Viticultural Area (AVA).

It lies in northern Santa Barbara County, according to the boundary description and USGS maps, and is entirely within the Central Coast viticultural area.