The Petaluma Gap is a geographical region in

Sonoma County, California Sonoma County () is a county (United States), county located in the U.S. state of California. As of the 2020 United States Census, its population was 488,863. Its county seat and largest city is Santa Rosa, California, Santa Rosa. It is to the n ...

which extends in a band from the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

San Pablo Bay San Pablo Bay is a tidal estuary that forms the northern extension of San Francisco Bay in the East Bay and North Bay regions of the San Francisco Bay Area in northern California. Most of the Bay is shallow; however, there is a deep water ch ...

. It is an area of low land 22 to 31 miles (35 to 50 kilometers) wide in the

coast ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Although the ...

of the northern San Francisco Bay Area. The western edge of the gap is located in the coastal lowlands between

Bodega Bay Bodega Bay ( es, Bahía Bodega) is a shallow, rocky inlet of the Pacific Ocean on the coast of northern California in the United States. It is approximately across and is located approximately northwest of San Francisco and west of Santa Ros ...

and Tomales Bay. The eastern edge of the gap is located at San Pablo Bay around the mouth of the

Petaluma River The Petaluma River is a river in the California counties of Sonoma and Marin that becomes a tidal slough for most of its length. The headwaters are in the area southwest of Cotati. The flow is generally southward through Petaluma's old town, ...

. The city of

Petaluma Petaluma (Miwok: ''Péta Lúuma'') is a city in Sonoma County, California, located in the North Bay region of the San Francisco Bay Area. Its population was 59,776 according to the 2020 census. Petaluma's name comes from the Miwok village nam ...

is near the center of the gap. The Petaluma Gap affects wind patterns (and thus

microclimate A microclimate (or micro-climate) is a local set of atmospheric conditions that differ from those in the surrounding areas, often with a slight difference but sometimes with a substantial one. The term may refer to areas as small as a few squ ...

s and air quality) in the

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...

. Fresh marine air generally blows eastward through the gap, branching into southward and northward streams which blow toward the Carquinez Strait and

Santa Rosa Santa Rosa is the Italian, Portuguese and Spanish name for Saint Rose. Santa Rosa may also refer to: Places Argentina *Santa Rosa, Mendoza, a city * Santa Rosa, Tinogasta, Catamarca * Santa Rosa, Valle Viejo, Catamarca *Santa Rosa, La Pampa * Sa ...

respectively. The southward stream brings marine air overland into the central Bay Area from the northwest. Warm air rises from the land and allows cold, moist air, plus winds and fog to move into the area.

Petaluma Gap AVA

Vineyards have been prevalent in the Petaluma Gap since the 1880s. During the 1990s, the Sonoma County wine industry adopted the term ''Petaluma Gap'' to help differentiate its products. It is a sub-region of the

Sonoma Coast AVA The Sonoma Coast AVA is an American Viticultural Area in Sonoma County, California, United States containing more than , mostly along the coastline of the Pacific Ocean. It extends from San Pablo Bay to the border with Mendocino County. The app ...

. Wine grapes growing in the Petaluma Gap are said to be influenced enough by this climate to give its wines a distinctive character. Mornings in the region tend to be foggy, followed by sunny days and windy afternoons. The cool evening temperatures help to preserve the natural acidity of the grapes over an extended growing season. Although many varietals are grown, the Petaluma Gap is best known for its Pinot Noir, Chardonnay, and Syrah grapes. In 2006, twenty-four local organizations and individuals formed a promotional group called the Petaluma Gap Grape and Wine Alliance, now known as the Petaluma Gap Winegrowers Alliance. In February 2015, the PGWA submitted a petition to the Alcohol and Tobacco Tax and Trade Bureau (TTB) to establish the Petaluma Gap as a formally recognized American Viticultural Area (AVA). On December 7, 2017, the region was designated as

Petaluma Gap AVA Petaluma Gap AVA is an American Viticultural Area established on January 8, 2018 by the U.S. Department of Treasury’s Alcohol and Tobacco Tax and Trade Bureau (TTB). The area spans stretching through an inland valley from the Pacific coast ...

with an effective date of January 8, 2018.

References

Footnotes

Sources

Sonoma County Climatic Zones

{{coord, 38.25055, -122.69969, format=dms, region:US-CA_type:pass, display=title California wine Climate of California Landforms of Sonoma County, California