Grape growers are basking in the sunny weather — at least emotionally.

Physically, they are sweat soaked and tired from working long days to catch up on rain-delayed tasks and assess the damage from an unseasonably wet spring.

"This weather is just ideal," said Nick Frey, president of the Sonoma County Winegrape Commission. "Things are now growing rapidly."

It is a sharp contrast to the cool spring that has plagued growers, who are anxiously awaiting the first signs of grape formation to determine the extent of crop damage from the wet weather.

The late-spring storm that dropped up to 2 inches of rain during the first weekend of June likely cost Sonoma County growers tens of millions of dollars.

"We likely lost 10 to 15 percent of our crop due to the rain," said veteran grower Jim Murphy. "There is nothing I can do about it."

The torrential rain hit vineyards at a critical time of the growing season, when many vines had opened their flowers to begin the delicate process of self-fertilization that usually results in grapes.

Late-season rain can wash away pollen, or prevent the flowers from fully opening. As a result, even though the weather is now perfect for growing, fewer grapes are likely being formed.

"In two or three weeks we should have a good idea of where it is at," Frey said.

By then, clusters of BB-sized grapes in the earliest stages of formation will start becoming visible if fertilization has occurred.

Early blooming varietals, such as chardonnay, will begin to show first, as will vineyards in warmer growing regions, such as the Dry Creek and Alexander valleys. The most likely damaged were vineyards blooming when the rains hit.

"We were heavily into bloom when this rain came," said Murphy, who mostly grows in Alexander Valley.

Still, growers such as Murphy take it in stride.

"As doom and gloom as it was a week ago," he said. "You look outside ... and it's sunshine and warm temperatures. Nothing looks better than Sonoma County in spring."

Optimism blooms eternal for veteran farmers like Murphy.

"Growers are the biggest gamblers of all," laughed Brian Clements, a partner at Turrentine Brokerage, a Novato grape brokerage firm.

And this season, despite the early difficulties, growers' spirits are being levied by improving odds, he said.

"I think growers are feeling better than anytime they have during the last 24 months, even with the weather," Clements said. "That's because the grape markets are getting better."

After two years of significantly reduced grape demand, which resulted from a slowdown in fine wine sales due to the recession, growers are now seeing an improvement in grape sales and prices, said Clements and other brokers.

"It's not a hot market. It's not really even a good market. But it's an improving market," Clements said.

Unfortunately, due to the weather, the growers likely will have less to sell at year's end.

Most growers expect this season's harvest to fall short of last year, which was about 5 percent smaller than average due to a cool growing season that was followed by a damaging August heat wave. The smaller than normal crop cost Sonoma County growers about $88.4 million in 2010.

Coming into this season, growers already were expecting a slightly below average crop. That's because the size of a crop is partly determined by the previous year's spring weather, when the vine's internal mechanisms are set for the following year's growing season. A cool spring means the vine scales back its zest for next year's growing season.

With Mother Nature providing another cool spring this year, growers are already expecting a smaller crop in 2012.

"We have now had two hellacious spring times where Mother Nature just laid it down on us," Murphy said. "She came down and puffed up her mighty chest, and gave it to us."

Still, growers are holding out hope that a strong summer growing season will put them back on track this year, and they won't find themselves biting their nails in mid-November as they wait for the grapes to ripen in the shadows of gathering rain clouds.

"There are so many unknowns now, people are just guessing when they talk about this season's crop size," Clements said. "That's what makes it fun. It's also what makes it maddening."