Vineyards that have been dark and stick-like for months are beginning to show signs of life as buds break through the North Coast vines, signaling the start of a new vintage in Wine Country.

The vines in warmer regions like Carneros were among the first to show young buds that will gradually shoot into leaves and vines and, finally, clusters of plump grapes.

"Things are starting to come back to life," said Chris Bowen, vineyard manager at Hunter Farms in Sonoma Valley. "With the warm weather we've been having, and the rain, the soil's probably warming up."

The beginning of bud break signals the start of the 2013 grape-growing season, which will unfold over the next six months and culminate with the fall harvest. Chardonnay and pinot noir grapes, especially in warmer parts of the county, are often among the first to pop.

"We're definitely starting to see some bud break," said Steve Sangiacomo, partner at Sangiacomo Family Vineyards, which grows grapes in the Carneros, Sonoma Coast and Sonoma Valley AVAs. "It's getting the year going, so we're looking forward to it."

In Alexander Valley, leaves are sprouting here and there on the chardonnay vines, said J. Alex Vyborny, owner of Vyborny Vineyard Management, which manages 1,000 acres of vineyards throughout Napa, Sonoma and Mendocino counties.

"It's starting to move," Vyborny said. "Things are just dry, and there's no rain, no cold weather, so things are starting to pop."

The forecast calls for a decent chance of rain Tuesday and Wednesday, and temperatures may fall as low as 32 degrees overnight on Thursday.

Tender new buds are susceptible to damage from frost when temperatures fall below freezing, prompting vineyard managers to spray them with water to form a protective ice shield on the grapes, or to use fans to help control temperatures. The frost protection season generally runs from March 15 to May 15.

Napa is further along than Sonoma, because of the warmer inland temperatures and rockier soil, Vyborny said.

The cool, foggy air in the Russian River Valley tends to delay vine development in that area. Bud break in the west county should be right around the corner, said Duff Bevill, founder of Bevill Vineyard Management.

"Everyone's getting excited," Bevill said. "The official spring time is starting."

You can reach Staff Writer Cathy Bussewitz at 521-5276 or or on Twitter @cbussewitz.