A crew of about 20 workers early Sunday rapidly snipped pinot noir grape clusters from vines, an effort duplicated throughout the region as the grape harvest moved into hyper-drive with rain on the way.

"It's a blur," said Tony Bugica, vineyard manager for Bacchus Vineyard Management, who was out with the crew off of Highway 116 near Graton. "Everybody's trying to get it done before the rain."

Weather forecasters said the first of two cool rain storms is expected to arrive in the North Bay by Monday afternoon, then tail off Tuesday with a second wet front blowing in on Wednesday.

Vineyard managers were expecting perhaps more than an inch of rain, prompting the flurry of activity over the weekend.

"This puts the accelerator down," said Nick Frey, president of the Sonoma County Winegrape Commission.

The grape harvest already is smaller and later than usual due to overall cooler, wetter weather. This week's forecast doesn't help.

Wet weather adds to concerns of additional botrytis, or bunch rot, and the cool temperatures and rain will impact all-important sugar levels. Wet weather also makes the vineyards muddy, preventing vehicles from moving effectively.

Frey estimated more than 20 percent of the county's overall grape crop is in. That leaves most of the $400 million crop still on the vine as the first storms of fall arrive.

While some of the thicker skinned grapes like cabernet and merlot can handle the rain, some grapes could suffer, such as zinfandel and chardonnay, said vineyard managers.

"A lot of zinfandel has been harvested, which is good," said Frey. "The chardonnay left in the field is vulnerable."

There is plenty of ripe chardonnay and pinot noir grapes still in need of picking and managers said it'll be a scramble to get to as much as can be done before Monday afternoon, including round-the-clock efforts.

"We've got a monster day tomorrow, Glenn Alexander, Bacchus Vineyard Management owner, said Sunday.

"We jammed as much as we could into Friday, Saturday and today. Tomorrow (Monday) we'll keep on going," said Duff Bevill of Bevill Vineyard & Estate Management.

"It makes me nervous," said Scott Zapotocky, director of vineyards for Paul Hobbs Winery, where one Bacchus picking crew was working Sunday morning.

"It's exciting" too, Zapotocky said, as the always changing dynamics add to the challenge of the harvest.

The coming storms were expected to halt the picking for a few days, but 70 degree temperatures and dry weather is expected to return Thursday.

Wet days will at least give winery workers a chance to catch up with the fruit that's already arrived and needs to get into tanks.

"They can't empty tanks or rotate tanks quickly enough," said Bevill.

With Mount St. Helena and dark gray skies as a backdrop, workers Sunday at the Paul Hobbs vineyard spread out along four rows at a time. They moved through the pruned canopy as fast as they could to fill their baskets with dark blue clusters and raise the tonnage that can determine their pay. Bacchus pays at least $12 an hour, more, depending on the weight picked, said Bugica.

Bugica had been out on the midnight shift and later Sunday morning remained in the field, juggling duties including bringing coffee and donuts to the crew, giving an interview, monitoring picking progress at other sites, making work adjustments and preparations for the pending rain, as well as answering his phone, which rang steadily.

His ring tone is the iconic theme from the 1966 classic spaghetti western film, "The Good, the Bad and the Ugly."

"That's what this is," he said with a laugh, referring to the complexities of the harvest.