California’s late grape harvest of 2010: What it could mean

Days after record-breaking, triple-digit temperatures across much of the state, the 2010 wine grape harvest has officially lurched into gear, weeks later than normal, kicking off the final acts of one of the strangest California vintages in recent memory.

Just a little more than a week ago, the day before the autumnal equinox, Sonoma winemaker Merry Edwards had her harvest staff stuffing envelopes for a fall mailing and once again taking a mop to the floors of her barely used crushpad. Morgan Twain-Peterson, winemaker for Sonoma’s Bedrock Wine Co., wondered on his Facebook page about whether he should attend a late-afternoon yoga class. And in Napa Valley, Frogs Leap winemaker John Williams was whiling away the hours at a long lunch meeting with the sales team of his Japanese distributor.

Needless to say, not one of these winemakers was doing what she or he almost always is doing in the third week of September: picking grapes. Across the state, winemakers were eager for harvest, but the grapes weren’t ready to pick.

Even with the latest heat spell, most red grapes (and quite a few white grapes, Chardonnay especially) remain on the vine statewide, anywhere from 10 days to three weeks later than last year. Late-ripening varieties, such as Cabernet Sauvignon, Syrah and Petit Verdot, have been so far behind in some places that producers were worried they’d be lost to bad fall weather: rain, a cold snap or both.

“We’ve had late harvests before,” says Chris Carpenter, who makes Cabernets and blends for Cardinale and Lokoya wineries in the Napa Valley, “but never in my career have I seen it this late.”


While this inevitably is going to make 2010 more of a nail-biter than previous vintages, it also could prove to be one of the state’s finest harvests in years — delivering wines with lower-than-average alcohol, more vibrant flavors, plenty of color and more balance. Winemakers’ well-earned gray hairs would be a small price to pay.

When you look at the temperature charts, the numbers are dramatic. Most wine regions use “degree days,” a heat index that is a measure of accumulated degrees above 50 degrees during the summer season. A typical reading this late in the season for Oakville, the heart of Napa Valley, is about 2,700. This year, until the recent heat wave, it was at 2,300. In Paso Robles, typical is about 3,000; this year, it’s 2,200. Both areas are two to four weeks behind what’s considered normal.

In the mountains above Napa, in Sonoma’s outer coast growing region and in other coastal areas of Northern California, grapes that in past years would already be in a fermenter were just completing their coloring phase, called veraison. “We’ve picked this early in the past, the third week of September,” Nick Peay of Peay Vineyards on the outer coast of Sonoma said last week. “But our Syrah is still going through veraison, which is frightening.”

By all reports, 2010 has followed a classic La Niña weather pattern, only this year the pattern is more pronounced than people had bargained for. La Niña years typically follow El Niño years; both patterns are linked to ocean currents and the resulting water temperatures, which affect coastal weather patterns. In an El Niño year, water temperatures are higher, resulting in warm dry weather on the Pacific Coast. La Niña, though, is yang to El Niño’s yin: the ocean currents are cooler, resulting in lower coastal temperatures and a stronger-than-normal marine inversion pattern.

This year, bud break, the starting gate for any vintage, arrived late in most parts of the state. But the first part of spring was warm and sunny, and led to a strong early spurt — abundant winter rains had prompted lots of canopy growth — the green stuff that’s the engine for growing fruit. April and May, however, were unseasonably cool.

“This is a normal cyclical pattern for La Niña,” says Peter Cargasacchi of Cargasacchi Winery in the Santa Rita Hills. “If you were aware of that, you could incorporate farming practices based on the historical patterns of the weather.” For Cargasacchi, that meant leaving a cover crop between vine rows to suck up excess winter rainwater, then deficit irrigation to stimulate the vines into ripening — “to give them a sense of urgency,” he says.

But in June the Golden State experienced not only cooler temperatures but a stubborn coastal cloud layer that seemed never to break up. “June gloom” lasted well into July, and even into early August, causing the vineyard growth cycle to dawdle. “There were weeks when it didn’t get above 60 degrees before noon,” Cargasacchi says.

Persistent coastal fog can also lead to another cool weather hazard, mildew. To combat this, many growers, especially in the north coast region, thinned their leafy canopies to facilitate air circulation. A side benefit of this thinning is that the fruit is also exposed to what little sun there is, which can advance flavor and color development, especially in red wine grapes.

In the third week of August, a heat wave sent triple-digit temperatures across the state, and the exposed fruit, unaccustomed to such a radical onslaught, succumbed to sunburn damage, an extreme form of desiccation that can render the cluster unusable. As much as 40% of some vineyards were affected. Some winemakers even reported some latent stem damage, which affects vine circulation and flavor development.

Then the temperatures went cool again, and the waiting game commenced in earnest. In the weeks that followed, Lokoya’s Carpenter has been especially proactive in his mountain vineyards, trying to do what he could to accelerate the ripening process. “Every last bit of fruit that was still green was getting dropped,” Carpenter says. He added that if a fruit cluster wasn’t getting close to ripe, it was probably holding back the development of clusters that were further along. “We cut our losses, essentially.”

He also opened up the canopy to let in as much light as possible — but that left the fruit vulnerable to the second heat spike. “We had exposed the vines to capture heat and light, though we didn’t expect this kind of heat,” he says. “It was quite a worrisome weekend, wondering if we had overdone it or not.” The heat will certainly accelerate sugar development, however, and the vineyards that are lagging will have more of a fighting chance to get to full ripeness.

June gloom may have outstayed its welcome, but many producers reported that the vineyards were happier for it. “In a hot year, the vines can look a little scraggly by this time of year,” says Jason Haas of Tablas Creek Winery in Paso Robles, “but this year the vineyard looks a lot healthier, the leaves are still bright green, and we’re seeing some good, even ripening.”

Haas points out that in a normal Paso summer, temperatures frequently exceed 100 degrees, which stresses the vines so much that they shut down and stop producing nutrients to preserve moisture. This year, that has been a rare occurrence. The Tablas vineyards, he says, have fared well through the current heat: “One nice thing about the heat wave coming at this time of year,” he says, “is that the days aren’t as long.”

And when it finally reaches the fermenter, fruit quality is likely to be very high. “The fruit flavors are very strong,” says Larry Hyde, proprietor of Hyde Vineyards in the Carneros region of the Napa Valley. “The stuff that makes fruit taste fruity, compounds like esters and ketones, are sensitive to hot weather and tend to be vaporized in the heat of a warm season. But we’re finding great fruit flavors in all varieties, and high acidity.” All of this should be achieved at lower-than-normal sugar levels, which translate to lower alcohols and better-balanced wines.

As for this last burst of heat, Pinot Noir producers such as Merry Edwards seem the happiest — it has pushed many of Edwards’ Pinot vineyards to optimal maturity. “As of Saturday, we began crushing at maximum capacity,” she wrote in a hasty e-mail, “and will continue through this coming Saturday at least. In one week we will bring in 50% of our total production. Pinot quality looks off the charts; color is twice normal, with great tannins.”

Out on Sonoma’s far coast, where the temperatures hit 90 degrees on Monday, Nick Peay was clearly grateful for a little acceleration. “We are still later than ever,” he says, “but at least now there is hope for the Syrah.”