Sonoma, Napa vintners hope for warm days as problems of later harvest loom

Temperatures are set to hover around triple digits across California this weekend. That’s more heat than North Coast vintners have been hoping for to help make up growing time for Wine Country’s grapes after a start to this season that was wetter, cooler and later than usual.

North Coast vine and grape development has been delayed one to three weeks — depending on the appellation and vineyard — behind the pace of the last three drought-impacted seasons.

In Sonoma and Napa counties, there’s concern that later grape ripening could lead to a later harvest, and that could put fruit in the region’s billion-dollar crop still on the vine at risk of fall rains or wildfires.

“If we can get the grapes to hang out there as long as we would like, then we'll make great wines,” said Richie Allen, head winemaker since 2008 for Rombauer Vineyards near St. Helena.

“But if Mother Nature curtails that ability and forces us to pick earlier because of inclement weather, or it cools off so much at the end of the fall that we can't get grapes to the ripeness level we would like, that changes everything.”

The Napa Valley vintner would be expecting the maturing berries for white grape varieties, such as sauvignon blanc, to start changing color from green to golden around now.

But Allen said he doesn’t expect that key phase in grape ripening to happen in the North Coast for another four to six weeks.

So, instead of expecting such early-ripening varieties to be ready to pick in early August, it’s looking like the first picking won’t begin until early September.

Allen is hoping for significant rains to hold off until late November to harvest the remainder of later-ripening varieties, such as cabernet sauvignon.

“In a late harvest, usually what it comes down to is capacity — how fast you can pick, how much fruit you can take today and how many tanks you have,” Allen said.

“We're pretty lucky at Rombauer that we have a large amount of capacity in terms of being able to process fruit fast as well as tank space, but we'll still be pushed to the limit. If the season closes out like it usually does with a good rain, it'll be trying.”

Above-average winter rains stretching through April pulled the North Coast and most of California out of drought, filling the region’s public and private reservoirs while replenishing aquifers and soil moisture.

For example, the Napa State Hospital weather station has measured 32.5 inches of rain so far this water year, which started Oct. 1, 2022.

That’s 123% above normal, far above the all-time low of 9.4 inches in 1923–1924 but still below the record 48.6 inches in 1982–1983, according to the weather service.

What Allen and other vintners are watching is whether the forecast return of the El Nino will result in earlier, heavier rains.

The National Weather Service is estimating that the ocean temperature phenomenon will strengthen this fall and winter, causing California temperatures to be warmer than normal in October through December.

Those warmer temperatures won’t necessarily mean more or earlier rain, according to forecaster Brian Garcia.

“This year is a bit of a wild card right now,” he said.

He said forecasters will be watching during this El Nino cycle for signs of an early atmospheric river, bringing potentially heavy rains to California. A harbinger is whether mid-October cyclones in the western Pacific Ocean pick up tropical moisture and move it to weather systems in higher latitudes that will move east toward the West Coast.

The rain-soaked winter and cooler-than-normal spring and summer have delayed more than just the North Coast this year, according to Glenn Proctor, partner of San Rafael-based Ciatti Co., which has wine and grape brokerage offices around California and the world.

“The whole state is late,” Proctor said.

The company is hearing that grape development is two to three weeks behind last year in the Central Valley and trailing by three to four weeks along the coast.

For example, a Ciatti rule of thumb is for grapes to be well into turning color in the Lodi area by the Fourth of July, but this year there’s little sign of that so far.

And Turrentine Brokerage’s North Coast grape dealer, Christian Klier, said this year’s cool days have led to an unusual flip in the pace of North Coast ripening this year, with early-ripening chardonnay and pinot noir grapes in Mendocino and Lake counties a few weeks ahead of the same varieties in Sonoma County.

That’s also what Randy Ullom, wine master for Jackson Family Wines, has been seeing among the Santa Rosa-based vintner’s over 12,000 acres of vines along the California coast.

“The weather has started to get better, but it’s not consistent, with four or five cold days then a few hot days then cold again,” Ullom said. “Once we get to nice weather of 70s, 80s and low 90s, we may be able to buy back time.”

At Rutherford Ranch near St. Helena, winemaker Marc Zaccaria is pleased that what rain did fall in 2021, plus the heavy rains in late 2022, set up the vines for healthy leaf and cluster growth this season.

Getting the balance right of vine leaf area to grape clusters, he said, helps with crop ripening, as clusters with unevenly ripening berries don’t have to be cut off, or “dropped,” so the vines can focus their resources on the remaining fruit.

Grape berry color change, known by the French term “veraison,” is expected to start in Rutherford Ranch’s mix of later-ripening red grape varieties — mostly split between cab and malbec — around the beginning of August.

“I’m hopeful we’ll have more warmth to carry us into veraison and into harvest without the crazy heat and rain in September 2022,” Zaccaria said.

Up to a few inches of rain fell across Napa and Sonoma counties Sept. 17–19 last year, after more than a week of 100-degree temperatures around Labor Day. But with the earlier start to last year’s wine grape harvest in the North Coast, vintners pushed to get the rest of the white grapes picked before the heat wave.

Yet growers and vintners reported that typically later-ripening red grapes shriveled a bit from dehydration during that heat.

Sonoma County’s Dry Creek Valley endured nine days over 100 degrees during that heat spike, said Lance Blakeley, head of vineyard operations for Pedroncelli Winery.

The vintner’s zinfandel grapes were ready to pick before, but the cab, merlot and cabernet franc grapes had to sweat it out. That shrunk the estimated tonnage by 20% to 30% and left the cellar crew with having to manage fermentation of juice with much higher sugars (at 28–29 degrees Brix, compared with the typical target of 24–26).

“We’re hoping for no extended heat spells,” Blakeley said.

At Gary Farrell Winery near Healdsburg, winemaker Theresa Heredia is looking to start harvest of pinot noir and chardonnay grapes from around Sonoma County at the end of August or beginning of September.

Last year, that was done on Aug. 12.

Cool weather, some wind and a little rain in early June has resulted in rare cases of cluster “shatter” — grape flowers that won’t develop, or “set,” into berries — in fruit the winery is buying from a vineyard near Sebastopol, Heredia said.

But otherwise the crop is shaping up to be on par with pre-drought sizes, or about 450–490 tons for the winery.

“We’re probably close to our targets because the fruit set looks good,” she said.

Jeff Quackenbush covers wine, construction and real estate. Reach him at jquackenbush@busjrnl.com or 707-521-4256.