As the summer days stretch long and hot, and grapes thicken with sugar on the vine, wineries are clamoring to ensure they'll have enough space in tanks and barrels to fit the fruits of an early harvest.

Growers anticipate the grapes will be ready for picking two to three weeks earlier than usual, and many are expecting the size of the harvest will be average or larger.

That has some wineries scrambling to add capacity in their storage rooms, or to book additional space in the custom crush facilities that dot Wine Country.

"There's a couple of wineries out there that are trying to put in new tanks, and they're rushing, and we've got people trying to put in new storage, and they're rushing," said Glenn Proctor, partner and broker in the San Rafael office of Ciatti Company, a wine and grape brokerage. "And complicating things and making it more interesting, is this looks like it will be a relatively early harvest."

Finding the space to crush the grapes and turn them into wine was a challenge in 2012, when a record crop sent more than 267,000 tons of grapes from Sonoma County vineyards into the wineries. Some of those wines are still aging in tanks and barrels, and have yet to find their way into bottles.

Major companies like E&J Gallo and Constellation Brands are expanding their cooperage capabilities by adding barrels or tanks, said Brian Clements, vice president of Turrentine Brokerage. Wineries that don't have enough room in their own facilities also turn to custom crush facilities that handle the winemaking process, but they're running out of time to line up the dwindling available space.

"If people that need custom crush space haven't confirmed it or reserved it, I think they may see a problem down the road in the next couple of months," Clements said. "This year, if the crop holds, if people are thinking they'll just do custom crush later, they may be surprised that there's not as much space as they think, and the price may be higher than they thought."

Custom crush facilities, which are busy pumping wine out of tanks and barrels and into bottles to make way for the 2013 harvest, are finding a lot of demand for any available space.

"There's definitely more activity," said Robert Morris, president of Punchdown Cellars, a Santa Rosa-based custom winery that works with more than 40 wine brands. "We've been lucky that we've had to turn away business this year."

Sonoma Wine Co., which process about 5,500 to 6,000 tons of fruit per year between its two North Coast crush facilities, is pretty booked up for the approaching harvest, said Natasha Granoff, director of business development.

"Because of the big 2012 harvest, we're jammed packed," Granoff said. "We're bottling out the 2012 to accommodate the coming vintage.

"If this harvest is average or above average, it's going to be pretty challenging, for some people who haven't bottled out, or for those people whose 2012 stay in tanks longer than a year," Granoff continued.

Sonoma Wine Co. doubled the tank capacity in its American Canyon facility over the last three or four years, Granoff said.

Requests for space have been rolling in earlier than usual at Rack & Riddle, the custom crush facility in Hopland that handles winery clients from Mendocino and Sonoma counties. The company started a waiting list in June, about two months earlier than normal, said Bruce Lundquist, managing member.

"If the crop is as large as some folks are predicting it is, I think it's going to present some challenges in the months ahead in terms of crushing space," Lundquist said. "I know there's 2012 wine that's not going to find its way to the bottle by the time harvest arrives."

The rush for space has been a boon for local tank manufacturers.

Westec, a Healdsburg tank manufacturer that usually lays off workers during the slow off-season months, has kept its workforce busy throughout the year, said Jim Belli, general manager.

"There's a much greater need for more storage than there was in the past, just because our markets have grown," Belli said. "We're not just selling down the street, we're selling to China and around the globe now."

For clients in the Central Valley, Westec has been building stainless steel tanks with the capacity to ferment and store up to 90,000 gallons of wine.

Santa Rosa Stainless Steel has been busy welding tanks for new and existing wineries, said Nathan Williams, head of sales. The company built about 435 tanks last year, and will probably make even more this year, he said. It typically generates $8 to $12 million in annual revenues, he said.

"There are quite a few expansions going on," Williams said. "There's still not enough space, so people are still buying tanks."

Rodney Strong Vineyards is among those that have increased its cooperage in the past year, said Robert Larson, public relations director.

"We had some space issues last year, because we had a new vineyard coming on, just above Lake Sonoma," Larson said. "But as a result of last year we prepared ourselves pretty well here, with the proper number of tanks and all that jazz."

Barrel companies also have been busy filling orders. Canton Cooperage, a Kentucky-based barrel manufacturer with a sales office in Windsor, has been challenged to keep up with demand, especially for its barrels made with 4-year-old wood, said Bruno Remy, vice president of sales.

"Last year, we could not offer these barrels, and we closed all the sales in July, more or less," Remy said. "After July, everyone who was contacting us was told we could not have any more barrels for the rest of the year, because the wood was already used or in inventory for orders to be made."

The company, which employs 48 people globally, sold about 15,000 barrels worldwide in 2012, up 5 to 10 percent from the year before. It is on track to sell that or more this year, Remy said.

Even though there's anticipation for what many believe will be a sizable crop, there's no telling how the weather may change that outlook over the next few weeks.

"The biggest obstacle that we have at this point is what Mother Nature is going to give us," Morris said. "There's so much time between now and when the fruit starts rolling through the door, that there's a lot of variables."