The Sonoma County grape harvest is at least two weeks behind schedule, worrying growers that October rains could lead to devastating mold and crop loss.

"It's a major concern," said Nick Frey, president of the Sonoma County Winegrape Commission. "The cold weather this week is certainly not helping any."

The season got off to a late start in May, when unusually cold and wet weather interrupted the blooming of many vines.

"This year has been behind from the get go," said Chris Bowen, vineyard manager of Hunter Farms south of Glen Ellen.

Bowen is often the first to begin harvesting in Sonoma County because his pinot noir grows in a region unusually warm for sparkling wine grapes.<NO1><NO> Last year, he started harvesting Aug. 10. This year, he expects he will be waiting "at least a couple weeks" later than that to begin picking.

"Things just aren't moving very fast," Bowen said. "Ideally we would have 85 to 90 degree days right now."

So far this week the high temperature has averaged 67 degrees.

On Tuesday, the high was 68, just four degrees off the record low of 64 degrees set in 1986. Forecasters say it will warm to a high of 70 today and reach 83 by Saturday.

Only a small percentage of Sonoma County grapes have begun softening and changing colors, a process known as veraison, growers reported Tuesday.

At Hunter Farms, only about 10 percent of the grapes have started to soften into the juicy sweet crop that will be harvested.

In 1991, Bowen didn't start harvesting until Sept. 6.

"I think that is probably about as late as we've ever started," he said.

The primary risk of a late harvest is that early rains can spawn mold in the grape clusters. But there is an upside, too.

The elongated growing season can benefit the quality of grapes.

"We're going to have some really nice quality fruit with the longer hang times," said Bob Iantosca, director of winemaking at Gloria Ferrer Winery in Sonoma.

Gloria Ferrer, which is one of Sonoma County's largest sparkling wine producers and buys pinot noir from Hunter Farms, usually harvests its grapes earlier <NO1><NO>than other still wine producers and has less concern about early rains.

The pinot noir crop appears to be about 20 percent smaller than last year, Iantosca said. The chardonnay crop is about the same as last year.

Overall, Nick Frey predicted this year's harvest will be about average or slightly smaller than average. He predicted a harvest size of between 190,000 tons and 200,000 tons.