Even at 76-years-old, Joe Rochioli wakes at midnight to oversee the harvesters picking grapes from his vines in the pre-dawn darkness. It's a labor of love he's enjoyed since he started picking grapes as a boy in his father's fields.

But in all his years among the vines, Rochioli has never seen a crop like this. A cool summer followed by two intense heat waves took a toll on his rolling rows of chardonnay, pinot noir and sauvignon blanc grapes.

"It's probably one of the worst years that I've seen in the last 40 years," Rochioli said as his son Tom maneuvered a bin of freshly-picked chardonnay grapes up the steel conveyor and into the press. "We're going to lose a lot of money."

The size of the grape crop at Rochioli Vineyards and Winery in Healdsburg is down about 45 percent from last year, Tom Rochioli said. Sonoma County's grape crop last year was considered larger than average<NO1><NO>.

The cool summer conditions pushed the harvest three weeks later than usual. And like the grapes at other vineyards, many were lost to sunburn during the late heat wave.

But the conditions could result in higher quality grapes, some winemakers say.

Vintners have harvested about 30 percent of the grapes, but they're usually two-thirds of the way through the process at this time of year, said Nick Frey, president of the Sonoma County Winegrape Commission.

Grapes in cooler areas are especially tardy, he said, noting that some vintners in the Russian River, Carneros and the Sonoma Coast have not yet started picking.

"We're worried because we'll be harvesting up until November," Frey said. "We're certainly concerned that the lateness of the crop has put us in a much riskier position for a rain event."

The size of county's zinfandel crop could be down by as much as 30 percent this year compared to a year ago, Frey said.

At Sanjiacomo Family Vineyards in the foggy Carneros region at the southern end of Sonoma County, this year's pinot noir crop could be 25 percent smaller than last year's, said partner Steve Sangiacomo.

But he said the longer hang-time on the vine means the grapes could develop more intense flavors.

"From early indications, things are tasting very well," Sangiacomo said.

That's also what Frey has been hearing from vintners around the county.

"I think we're optimistic that we're going to produce some good quality wines, and it's a question of how much," Frey said. "Every day we can harvest now is critical, so we want to take advantage of them all."