The strong weekend storm that drenched the North Bay landed a staggering blow on area grape growers, who are now racing to complete the harvest before mold and another looming storm provide a knockout punch.

The two-day front walloped Wine Country, dropping 4 inches on many parts of Sonoma County and causing minor flooding, power outages and widespread road problems.

The storm also set up a tight race against the clock for grape growers. Many were rushing to complete their harvest last week, and for those who didn't — officials estimate that as much as 15 percent of the county's grapes are still on the vine — the weekend rainfall will mean a quick, muddy march to the finish.

"We're getting near the end," said Nick Frey, president of the Sonoma County Winegrape Commission. "This is the final blow."

The specter of a mold breakout, especially in the more thin-skinned chardonnay grapes, and the arrival of more wet weather Thursday have growers gearing up for a last push to wrap up what's already been a tough year.

After an unusually cool summer, crews at St. Francis Winery and Vineyards didn't start harvesting the 600 acres until Sept. 27, the latest date in the Sonoma Valley property's history.

"We didn't pick because the fruit wasn't ripe," said St. Francis president Christopher Silva. "Now we're trying to bring in as much as we can as quickly as we can."

At Dutton Ranch near Graton, picking crews will focus exclusively on the remaining 400 tons of chardonnay grapes. A smaller number of syrah grapes will likely stay on the vine through the coming storm.

"They can handle the rain," said owner Joe Dutton. "They won't rot like chardonnay."

Yet soggy vineyards will likely complicate matters, requiring a switch to lighter equipment that doesn't bog down in saturated soils, but which makes the harvest go slower, growers said.

Ned Hill, owner of La Prenda Vineyard Management, which oversees 420 acres in the southern end of the Sonoma Valley, said the 3 1/2 inches that fell in the area over the weekend made planning for the final days of harvest difficult. He was surveying vineyards Sunday night to see which ones would be dry enough to withstand traffic.

"The grapes, especially if we can get them picked quickly, are still in okay shape," he said. "It's just how do we get it done?"

The storm tapered off Sunday evening, but only after leaving its mark across the region, taking trees and power lines to the ground throughout Sonoma County.

The rain and wind took down 50 trees around the county, mostly in the western reaches, Sonoma County fire officials reported.

In Sebastopol 3,654 residents lost power at about 11 a.m. Sunday morning, said J.D. Guidi, spokesman for PG&E. And in Geyserville, 1,240 residents lost power at 12:50 p.m., Guidi said. PG&E expected to restore power to most residents by Sunday night.

More than 3 inches of rain fell on Santa Rosa, Sonoma, Rohnert Park and Cloverdale between 4 p.m. Saturday and 4 p.m. Sunday. Cazadero, as usual, was the wettest part of the county, receiving 7.95 inches of rain during the 24-hour period.

Further north, heavier rains fell on Mendocino County, where the small community of Leggett soaked up 8.32 inches of rainfall over the same 24-hour period. That was the highest amount recorded in the state, said Steve Anderson, a forecaster for the National Weather Service.

The National Weather Service issued a flood advisory for urban and small creeks in Sonoma, Marin, Napa and Contra Costa counties.

The CHP reported flooding on parts of Highway 101 south of Windsor, on both Highway 101 and Highway 116 in Cotati and on Highway 12 just west of Sebastopol.

"We had the typical flooding throughout the same spots that we always have, every year, during heavy rains," said David Derczo, acting sergeant for the CHP in Sonoma County.

The region will dry out on Monday, Tuesday and Wednesday, Anderson said. But more wet weather is coming. After midweek, there is a 30 percent to 50 percent chance of rain every day from Thursday through Sunday, Anderson said.

"It's a little unusual that it came a little early," Anderson said about the winter storm. "Typically we'll see this kind of rainfall at the end of October through the middle of November."

For some, the storm provided a day of rest. It arrived as the Giants punched their ticket to the World Series and, in Wine Country, after a nearly sleepless week of all-out harvesting.

Rob Davis, the winemaker at Jordan Winery in Healdsburg, brought in the last of his grapes Friday, hours before the first drops fell.

"I felt so bad for other growers. I just saw so much fruit that was still out there that wasn't coming in," he said.

Still, fickle and unpredictable as they may be, such signs from Mother Nature are a clear closing bell on the year for grape growers, he said.

"To have one rainstorm bring in so much moisture — it's nature's way of saying &‘It's time to start thinking of Thanksgiving. Harvest is over.'"