SAN FRANCISCO — California vintners are bringing in the grape harvest this month after a challenging year that started with unusually sharp frosts and moved on to smoky summer wildfires.

So far, it looks like the crop will be smaller than usual but the fruit that is coming in is good, said Karen Ross, president of the California Association of Winegrape Growers.

"Last week was crazy, reds and whites were coming in," Ross said. "This week has slowed down, but it's still going at a fairly good pace in the (Central) valley."

The grapes are smaller than usual this year, but, "people are very happy to date with the quality and flavor development," she said.

Harvest caps a season that began with late frosts that struck just as vines were beginning to send out shoots. That was followed in some areas by a heat spike that hit during flowering, more adversity, said Nick Frey, president of the Sonoma County Winegrape Commission.

"We have had some real tough spots," he said. On the plus side, conditions for much of the season were "pretty ideal," he said.

Lightning-sparked summer wildfires cast a smoky blanket over large swaths of the state. It wasn't clear if that would affect the grape crop, but some wineries are having juice tested as a precaution, say industry observers. "At this point everybody's watching," said Domingo Rodriguez, co-owner of Winesecrets, a company that filters unwanted substances out of wine.

If grapes are affected by smoke taint, the wine could have off-flavors, said Rodriguez. Filtering the wine removes compounds associated with smoke taint, he said.

In Sonoma County, Frey said he hasn't heard any reports of smoke taint, "and certainly they've been tasting a lot of grapes and by now they've been tasting a lot of wine." Jennifer Kopp Putnam, executive director of the Napa Valley Grapegrowers, said she, too, hasn't heard of smoke problems.

Paul Dolan of the Mendocino Wine Co. in Mendocino County, which saw about a month of smoky haze, said his grapes seem fine so far, but that he has seen damage elsewhere in the region.

For individual producers, that could be a problem, "but as far as the impact on Mendocino County, it'll be just a small blip on the radar," he said.