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Pinot noir grapes hang on the vine in the rain at Estancia Estates vineyard in South County.

Now home to dozens of world-class vineyards operating 40,000 acres, Monterey County was once thought to be too cold, dry and windy to grow the delicate wine grape.

Over the past 75 years, science has upended that perception, making the case for Monterey County as a premium wine region.

And the forces at play aren't coming from the valleys, but from deep in the ocean.

As far back as 1935, landmark climate studies by UC Davis horticulturists Albert Winkler and Maynard Amerine classified the grape-growing climate in Monterey County as comparable to Napa, Sonoma, Burgundy and Bordeaux.

At the time, "there were some very limited plantings, mostly for personal use," says Larry Bettiga, viticulture farm adviser to the University of California Agriculture and Natural Resources Center. "There were very few commercial operations."

It was not until the 1960s, when increased urbanization of the Santa Clara and Livermore valleys led vintners to reconsider Salinas Valley as the home for their new vineyards, that winegrowing really began to flourish in the region.

According to wine historian Leon Adams, writing in his seminal book "The Wines of America," the research of Winkler and Amerine directly led to Monterey County becoming "the world's first wine district established as the direct result of scientific temperature research."

Initially, warm-weather red grapes were planted in the northern part of the county, but growers soon realized cooler-weather grapes


would do better. Eventually, as vineyards spread south through Salinas Valley, red varietals took hold.

"The unique thing about Monterey County is we have such a range of different climates," Bettiga says.

The microclimates contribute to the large number of varieties — 19 white and 23 red — that can be grown on the more than 200 vineyards in the county. Vineyards in some of the county's cooler microclimates have the latest crush in California, often lasting into early November.

What is it that makes the county so inviting to so many varieties of the thin-skinned, juicy orb?

A lot of the credit goes to the enormous canyon that lies beneath the surface of Monterey Bay. This submarine wonder runs 60 miles long, stretching from Cambria in the south to San Francisco in the north, and dives two miles deep, as deep as the Grand Canyon in many places.

The canyon, which formed 2 million years ago, is nestled within the Monterey Bay National Marine Sanctuary. Its proximity to the shore makes it unique among underwater canyons of its size, and creates a climatic bridge between the cold, deep water of the canyon and the winegrowing fields in Salinas Valley.

"There are few areas in California that are true coastal valleys that have a direct opening to the Pacific," Bettiga says. "Salinas Valley is the largest one."

Wind tends to run north to south along the California coast. As the wind pushes warm water near the surface away from shore, colder water near the bottom of the canyon is driven up. The cold water chills the wind blowing over the ocean as it hits land, generating fog.

Each morning, as the sun rises, the southern end of Salinas Valley warms up. This creates a low-pressure effect that sucks the cool, foggy air over the ocean down the length of the 90-mile-long valley.

"It's like turning on an air conditioner every afternoon," says Bettiga.

The effect is enhanced by the southeast to northwest orientation of Salinas Valley, says Wendell Nuss, professor of meteorology at the Naval Postgraduate School.

Unlike most marine-influenced river valleys and winegrowing regions, which are oriented east to west, Salinas Valley "is very well situated to get prevailing flow off the Pacific," Nuss says.

As cool air moves farther away from Monterey Bay throughout the day, it gradually heats up from 50 to 70 degrees, creating many distinct microclimates along the length of the valley.

This climatic variability contributes to growers planting cool-climate varietals such as pinot noir and riesling closer to the ocean and Bordeaux and Rhone varietals in the southern regions, away from the marine influence.

Nuss says Monterey Bay's deep canyon also keeps area temperatures within a moderate range, which has a number of positive effects on grapes.

"It's the absence of really hot days that accentuates some of the flavor components in these wine grapes," Bettiga says.

Steve McIntyre, owner of McIntyre Vineyards in the Santa Lucia Highlands, also attributes enhanced flavor to the area's unique weather. He says the coolness and humidity associated with the area's fog gives wine "more flavor than wines over in Fresno or the interior."

The moderate temperatures also mean Monterey County is generally less affected by frost than other growing regions, making buds break earlier. In spite of the early start, harvest often continues into mid-November, partly because of the region's wind.

The relatively strong winds that flow down Salinas Valley make the small pores on the surface of grapevine leaves close, slowing down growth. According to McIntyre, who holds degrees in viticulture and enology, the slowdown ultimately increases grape hang times, contributing to the longest growing season in California.

"It generally means we are going to download more of everything other than sugar that we are looking for, such as aroma precursors and phenolics," says McIntyre.

Chris Palmer can be reached at 646-4494 or