A severe frost hit Northern California on the weekend of April 19 and 20, with nighttime temperatures dropping to the high 20s in some vineyards. The late-season frost came at a critical time since blooms were still fragile on vines across the state. Growers from Napa and Mendocino to the Central Coast are still walking their vineyards to assess damage.
Cold weather this spring has been an unusually rigorous challenge, and this was the worst frost in more than 30 years, potentially causing millions of dollars' worth of damage in California's prime wine regions and leading to sleepless nights for growers and winemakers across the state.
"I can't remember a frost like this since 1972," said Andy Beckstoffer, who oversees some of the largest vineyards in Northern California. "I don't know if the damage is all that severe, maybe we've lost 10 percent, but we'll know more later."
Even a 10 percent loss translates into millions of dollars for California's lucrative wine-grape industry. Frost seldom has an influence on what consumers taste in the bottle, although it may sway the bottom line: As crop yields shrink, prices rise.
Frost is hardly unusual in California and in some years it can be severe, most recently 2001, and cooler regions such as Carneros, Russian River and Anderson Valley are usually hard hit, which means varietals like Pinot Noir and Chardonnay may bear the brunt. "It's a war out here," Goldeneye winemaker Zach Rasmuson said, tongue half in cheek, of the efforts made to protect his vines in Mendocino's Anderson Valley.
What distinguishes this season is the duration and severity of the frost season. Russian River winemaker Merry Edwards said that recent springs typically required two or three nights of frost protection—generally fans blowing to hamper frost from settling on vines or a protective coating of water that insulates the vines from damage—but this year was different.
"We have protected up to 17 nights in one vineyard," Edwards said, echoing many of the area's winemakers and growers. Rasmuson had a similar experience, using frost protection on 20 nights between March 25 and April 22. "2001 was a challenge because we were deluged on a particularly cold night or two," Edwards said, "but this is almost worse because it's so prolonged."
Central Coast had its share of frost but the growing season was several weeks behind the North Coast, so winemaker Adam Lee of Siduri believes the impact will be less in regions such as Santa Rita Hills and Santa Lucia Highlands.
In Northern California, growers were caught off guard this season because frost reached areas that seldom have issues, such as the upper regions of Dry Creek and Alexander Valley. Many of those growers, who hadn't felt the need to protect from frost in recent memory, felt the hit. Not that it mattered, Beckstoffer said, "We had great protection and we were still damaged."
Long-term concerns remain. Growers in dry regions such as Anderson Valley were forced to use precious water reserves to protect from frost, and may feel the pinch later on in the season. And Edwards cautioned that nature is sometimes a poor manager of quality—frost is notoriously uneven and seldom makes the best selections in the vineyards.
That said, Rasmuson recalled the frost of 2005, which hit Anderson Valley in particular. "Those Pinot Noirs," Rasmuson said, "were some of the best that Anderson Valley produced."
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