There's excitement in the air as winemakers across Sonoma County hurry through final preparations, or catch their last bit of rest, before the onslaught begins.

The North Coast grape harvest is expected to kick off next week, several weeks later than normal as a result of cool spring weather that slowed the maturation of the region's $1 billion grape crop.

"I have the pre-harvest butterflies a little bit, and a general sense of hope that you have before harvest," said Melissa Stackhouse, winemaker for J Vineyards & Winery of Healdsburg. "Because who knows, it could be really stellar. Harvest unfolds as we're going through it, and that's the nice mystery about it."

In the wee hours of Monday morning, grape pickers will set out at J Vineyards to begin picking pinot noir and chardonnay grapes used to make sparkling wines.

The winery expects to harvest about 20 percent fewer grapes than normal this year, spokesman George Rose said. Rains in June simply knocked the flowers off the vine, so there were fewer berries in each cluster, he said.

"Our winemaking team definitely is gearing up for what they like to refer to as war," Rose said. "It's a very grueling process."

Despite the cool temperatures, vineyards in Alexander Valley and Dry Creek Valley have accumulated about five or six more days of warm temperatures than the same time last year, said Nick Frey, president of the Sonoma County Winegrape Commission.

"We're going to have the long hang time that winemakers want for flavor depth, but I think we're in a better position than last year," Frey said.

The lighter crop is making some grapes ripen faster on the vine, said Chris Bowen, vineyard manager for Hunter Farms in Sonoma Valley. With fewer grapes, the sugar produced by the leaves makes its way inside the grape faster, he said.

Bowen estimates Hunter Farms will start picking pinot noir grapes for sparkling wines in the middle or end of next week for Gloria Ferrer Caves & Vineyards.

"I'm hopeful that we don't have another harvest like last year, because last year was just slam-bang. We had no letup," Bowen said. "It would be nice if things went smoothly. They never do."

Bowen is expecting to harvest about 25 percent fewer pinot noir grapes than an average year. Chardonnay grapes don't look quite as bad, and some of his merlot and cabernet grapes look good, while others don't.

To the west in the Russian River Valley, Iron Horse Vineyards is poised to start picking grapes for its sparkling wines in about 15 days, based on the sugar content of the grapes, winemaker David Munksgard estimated.

"It's kind of like crystal ball-ing right now," Munksgard said.

When J Vineyards starts picking, Munksgard can practically set a clock and assume Iron Horse's grapes will be ready for picking within a week or two.

Iron Horse is racing to get bottling done now so it can hopefully give the crew a long weekend off before the madness of harvest begins.

"There's all kinds of obstacles in your way, but at the end of the day, after all the agonizing and worry about the harvest, it's suddenly here," Rose said.