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Harvest report: Cool temperatures produce optimal conditions for ripening

From the Series: Napa Valley Grape Harvest 2018 series
Pinot Noir harvest at Trefethen

Trefethen team members Moices Dorado-Zamora and Pedro Castro, trusted to keep stray leaves out of the bins, show off the clean Pinot Noir at Trefethen on their first day of harvest.

Grapegrowers are celebrating cool temperatures that are leading to a slow, even ripening process in Napa Valley vineyards.

Jennifer Rue of Oakville Ranch Vineyards referred to “Goldilocks days” that are “perfect for field work.”

A streak of unusually early harvests seems to have ended this year, with this year’s harvest one or two weeks behind the pace of last year’s.

“The cooler weather in the last week of August has been called everything from blissfully normal to perfect,” writes Dawnine Dyer of Dyer Vineyards. “Whatever you call it, it’s been great for the vineyards on Diamond Mountain, extending the season and building desirable flavors and tannins … so far so good.”

Here’s this week’s harvest report, organized by American Viticultural Area (AVA):

Calistoga — Matt Crafton, Chateau Montelena — “This weather is as good as it gets, as the marine layer has persisted until almost noon, and afternoon temperatures haven’t surpassed the low 80s. Slow, predictable ripening is exactly what we’re looking for, and while this has certainly slowed activity in Calistoga, it’s a welcome relief after a string of early vintages. Here at Montelena, we brought our first fruit in on Monday, a brand new block of Chardonnay from our ranch in Oak Knoll. A great start for 2018.”

Howell Mountain – Laura Barrett, Clif Family Winery — “The past seven days have brought mild temperatures to our tail end of summer. We have seen highs in the low 80s with nighttime temperatures dipping into the mid-40s and it’s starting to feel like fall on Howell Mountain. With that, we are seeing even development, low irrigation needs, consistent coloration, healthy canopies and the beginning of sugar accumulation in Cabernet Sauvignon. Ron Haber of Haber Family Vineyards has noticed the fog lifting much later than normal. And Brian Brakesman reports ‘even ripening and a nice reprieve from the heat’ at his Summit Lake Vineyards.”

Diamond Mountain District — Dawnine Dyer, Dyer Vineyards — “As August draws to a close, the start date for harvest on Diamond Mountain is still being counted in weeks, not days. Even von Strasser’s Gruner Veltliner is only 17.8 Brix and most winemakers won’t even start sampling until after Labor Day. The cooler weather in the last week of August has been called everything from blissfully normal to perfect. Whatever you call it, it’s been great for the vineyards on Diamond Mountain, extending the season and building desirable flavors and tannins … so far so good.”

Chiles Valley District — Alexander Eisele, Volker Eisele Family Estate — “Sampling of whites has begun but no fruit has been harvested. At this point we are two weeks behind the last couple of years. Verasion in Cabernet is almost complete. Sauvignon Blanc at about 20-21 Brix and Semillon 18-19 Brix and Chardonnay at 15-16 Brix. If the cooling trend continues, we could be pushed even further behind.”

Spring Mountain District – Stuart Smith, Smith-Madrone — “Most of the red grapes on the mountain still have not finished veraison and it will be another week or two before anyone begins harvesting the whites. Both Ron Rosenbrand at Spring Mountain and Matt Gardner at Keenan are very pleased with the way the vines are looking with strong, robust and healthy canopies. Even after hedging back, many of the vines still have growing tips, which is a very good indication of ample soil moisture.”

St. Helena – Torey Smith, Battuello Vineyards — “At Battuello Vineyards in St. Helena we are still about a couple weeks out on the start of harvest. Our Cabernet Sauvignon is currently sitting at 20.5 Brix level. The cool mornings and temperate weather have been slowing ripening.”

Rutherford — Kristin Belair, Honig Vineyard & Winery — “The forecast continues to be for below normal temperatures for most of the work week giving us plenty of time to walk vineyards and contemplate how harvest might progress. Subtle signs of fall are showing up across the valley with yellowing maple and black walnut leaves appearing and the buckeyes losing their leaves. Chris Phelps of Inglenook reported that they brought in their Sauvignon Blanc Friday and Saturday last week. It is showing ‘excellent, well-developed stone fruit and citrus flavors, perfectly fresh acidity and only 13 percent potential alcohol.’ The vines seem to be appreciating the cooler weather and rewarding us with some lovely flavor development. At Honig, we are anticipating our first Rutherford Sauvignon Blanc to arrive at the end of the week.”

Oakville – Jennifer Rue, Oakville Ranch Vineyards — “Cooler temperatures and marine layer materialized as expected last week. These Goldilocks days are perfect for field work while taking in the green canopies and well-set clusters of this non-drought year. You’ll hear no complaints from Oakville. Last year at this time we were in the midst of a brutal 12-day heat storm that sent sites into a hard stall. The white grapes rolling into and through Oakville are still from outside the AVA and we’re an easy month-plus away from harvesting reds. Until then it’s watching and waiting time.”

Atlas Peak — Gordon Waggoner, Acumen Wines — “With veraison nearly complete, ripening is continuing at a near-perfect pace. With many sites on Atlas Peak above the fog-line and with southwestern exposures, we have good, even warmth and nice sunshine hours. Coupled with our typical afternoon breezes, this is providing great conditions for sugar accumulation without much additional irrigation needed, plus low mildew pressure. This will allow for deep, complex flavor development. We are already seeing seed browning in some blocks, so phenolic ripeness levels look very promising for the vintage. We’re very excited about overall 2018 quality heading closer to harvest.”

Stags Leap District — Elizabeth Vianna, Chimney Rock Winery — “This week continued to gift us with beautiful ripening weather here in Stags Leap District. Veraison hit the finish line thanks to foggy cool mornings and perfectly warm days. Remi Cohen, vice president at Cliff Lede Vineyards, shares that they began sampling their early Stags Leap District blocks and predicts a mid-September start. ‘We are excited about the vintage; the crop went through veraison uniformly, vines look healthy, and it appears to be at least an average-sized crop,’ Remi reported. At Chimney Rock, we started sampling our hillside Merlot and found it’s running about a week behind last year. Our team’s excitement is palpable as adrenaline starts to build for our favorite season.”

Mount Veeder — Lorenzo Dalla Brea, Hess Collection — “Last week’s temperatures were very mild, with some fog in the early morning to further chill down grape clusters. Veraison is moving along, with now almost 100 percent of the clusters turning in color in our Cabernet Sauvignon, Malbec and Merlot blocks. Our Estate Chardonnay grapes are developing in the varietal flavor profile, with sugars now testing between 19.5 and 20.5 Brix. In the Mount Veeder appellation we generally see lower Brix than other areas in the Napa Valley at this time of the season and as a result, we do not anticipate any harvest on Mount Veeder happening before Labor Day.”

Oak Knoll District – Jon Ruel, Trefethen Vineyards — “This week’s harvest in our region included more Pinot Noir for sparkling wines and the earliest blocks of Chardonnay and Sauvignon Blanc. The weather has been cool over the past couple weeks but flavors have continued to develop nicely. The pace of harvest in September could be hectic if temperatures rise again.”

Coombsville — Tom Farella, Farella Vineyards — “The weather has remained cool, for the most part, and the vines are still turning the corner on most varietals. We are still green-thinning at the late stages of veraison in Cabernet and Merlot so most reds are a ways off still. We anticipate picking Sauvignon Blanc next week with warmer weather in the forecast next weekend.”

Carneros – Christopher Hyde, Hyde Vineyards — “The cool weather spell continues in Carneros, with ripeness advancing very slowly in the vineyards. Crop levels appear above average this year, and canopy growth is strong. After an extended bloom period in the spring, we are now experiencing an extended veraison, ideal conditions for maintaining natural acidity and producing high-quality wines.”

For real-time harvest photos and updates, visit the Napa Valley Vintners’ Harvest 2018 website at

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Related to this story

With rain in the forecast, many correspondents report they’re very close to being finished with the 2016 harvest, if they’re not done already.

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