Mediterranean Climate: What Our Vineyard Sources Have in Common

Winemaker George Troquato

Most California winegrowers are quick to point out that their vineyards possess a maritime influence followed by a general explanation of how grapes benefit. While these claims are usually true, the regional nuances are often left on the proverbial cutting room floor. The following discussion presents an overview of the process and a few examples that will help you “connect the dots”.

Most California vineyards benefit from an authentic Mediterranean climate (aka a dry summer subtropical climate). These conditions exist in only a handful of areas worldwide, all on the western side of their respective continents: the Mediterranean Basin excluding the hot southeast, coastal California, central Chile, western and southern Australia, and southwest South Africa. This climate is framed by three main factors: temperature, precipitation and fog.

Regions with a Mediterranean climate lie near large bodies of water that moderate growing season temperatures, varying from warm to hot depending on proximity to the coast, elevation and latitudes.

These areas receive most of their precipitation in winter when the polar jet stream reaches lower latitudes. During the summer, they benefit from subtropical high-pressure cells that diminish the likelihood of rain with the wettest areas being in higher latitudes and western longitudes.

Fog is a common occurrence with Northern California being the most notable. This phenomenon is caused by the condensation of warm, moist Pacific air as it passes over the cold waters of the Japan Current.

Few wine regions can claim the divergence demonstrated by the Santa Cruz Mountains: the sheltered San Francisco Bay side versus the exposed Monterey Bay portion. Records reveal warmer temperatures and less rainfall among hillside plantings of the former. Winemaker George Troquato says that pinot noir from the Monterey Bay side shows ripe wild berry, briar, game and earth. “In contrast, pinot from the SF Bay side has less acidity and gaminess, but riper fruit,” he says.

One hundred miles east of San Francisco lies the Lodi-Woodbridge Appellation. Cabernet franc from this area benefits from the daily cycle of cold ocean air being drawn into California’s hot central valley on a meandering route through San Francisco Bay, San Pablo Bay, the Carquinez Straits, Suisun Bay and the Sacramento River Delta. This marine layer gradually warms before reaching Lodi in the afternoon, but retains enough coolness to mitigate the heat. Grapes achieve even ripeness, good acid development, and vine stress that thickens skins and enhances flavor.

The Paso Robles Appellation is halfway between San Francisco and Los Angeles. George selects merlot from the El Pomar district because the area maximizes the maritime influence created by a pass in the coastal mountains called the Templeton Gap: occasional fog, great diurnal temperature variation (85–105° days, 40–50° nights), dry conditions and profound afternoon breezes. The daily air movement stresses vines and causes a defensive reaction that thickens and darkens grape skins, resulting in greater flavor intensity.

A final and disparate example of Mediterranean climate lies in the Santa Lucia Highlands of Monterey County. “The maritime influence is always present,” says George, “it doesn’t come and go like in other areas.” Downwind from Monterey Bay, the area starts cool, then slowly warms up in the late morning. Fog is a frequent factor. George likes the region for whites and pinot noir — wines whose structure is dependent upon acidity. “The long growing season allows fruit to slowly develop complexity, flavors, acidity and varietal character,” he says.

~ if you liked this post, please share it