Yet Warnebold figures it could be a good year with the drought concentrating the fruit's flavours and sugar, which will turn to alcohol during fermentation. His red Norton and white Chardonel grapes, while small, hold the promise of standout wine from a region better known for corn and soybeans.
Wineries have been popping up in grape-growing regions of Missouri, Michigan and other Midwestern states for years, but they've generally been seen more as tourist draws than quality vintners. Some are hoping this year will help change that, and in a summer that has been devastating for most farmers, grape growers have a bit to cheer.
"The fruit will be better, overall, for reds and whites, then last year, when it was wet," said Tony Debevc, who has a 170-acre Ohio vineyard. "If it continues to be dry like this, the wine industry will be better overall. And personally, we can expand in the red category, and it wouldn't necessarily be a bad thing."
That's not to say everything is rosy. The drought still stressed the vines, making them less likely to survive a harsh winter and produce next season. But vineyard owners say the varieties commonly planted in the Midwest have roots that can reach dozens of feet below the surface to get at water tables, making them a bit more drought-resistant.
The harvest will almost certainly be smaller too. Warnebold figures he will get 2,500 cases of wine this year — 1,500 less than what he typically might expect — from his six-acre vineyard atop a bluff overlooking the Missouri River. But he routinely has set cases from each year aside as a hedge against "bad years," so there won't be a shortage.
This year's wines from America's heartland "will be nice, fruity and very approachable and soft on the pallet," predicted Diego Meraviglia, vice-president and education director for the California-based North American Sommelier Association.
But he believes the drought has cost some grape varieties complexities that may hinder the wines' abilities to age, meaning "you have to drink them within a year or they'll go bad."
"It'll be enjoyable right off the bat," he said. "But real connoisseurs who drink aged wine will be disappointed."
Warnebold bristled at the suggestion of a shortened shelf life. "I've been to a lot of wine conferences with a lot of wine experts, and I've never heard that theory before," he said.
Brad Beam, an Illinois Grape Growers and Vintners Association enologist, downplayed the debate, saying "a lot of our wine is best drunk on the young side anyway."
Vineyard owners in Ohio said they believe this year's drought is just a taste of what's to come with prospects that the climate generally is becoming warmer and dryer.
Debevc, who owns Debonne Vineyards in Madison, Ohio, said he planted some varieties two years ago that need warm weather, even though they weren't recommended for the area at the time. He said more permanent changes down the road could include harvesting earlier in the year and setting up drip irrigations systems to supplement rain in dry years.
"I think there is a trend I've seen in my lifetime. I've seen more storms than when I was younger," Debevc said. "I think we will adapt. For us in the vineyard industry, it's a good thing. A little more heat, a little more dryness. Personally, it would allow us to have much more mature fruits, certainly in the reds."
Duke Bixler, who owns Breitenbach Winery in Amish country near Dover, Ohio, also planted a variety two years ago that wasn't suggested by the industry for his part of Ohio.
"They're doing very well," he said.
Like Debevc, he's watching the weather and thinking about the future. Hot, dry conditions help red wines, he said, but they're not so good for the fruit and berry wines Breitenbach and many other Midwestern wineries offer.
"Certainly, here in Ohio, and northern Ohio, and the Midwest, I think our heat days are increasing, our sun days are increasing," Bixler said. "I think it is a permanent thing."
At the Stone Hill Winery he manages in Hermann, Jon Held worries the drought "might be the new normal," leaving him mulling investing perhaps $1,500 an acre for more irrigation as a hedge. But at least for this year in the winery's 190-acre vineyard, he said, "it's going to be an OK quality season, and you may actually have stellar quality on some varieties," notably among reds.
In Michigan, where Great Lakes breezes and hilly terrain nurture a rapidly growing wine industry, grapes seem to be one of the few success stories in a disastrous year for most fruit crops. An early hot spell followed by April freezes ruined most of Michigan's tart cherries, apples and other orchard fruits.
But grapevines emerged from dormancy and sprouted buds after the cold snap ended, and the dry summer protected the vines from diseases that run rampant when it's too rainy.
"I say it reluctantly, and knock on wood, but it's been a great year so far," said Mark Johnson, winemaker at Chateau Chantal winery on Traverse City's Old Mission Peninsula.
Associated Press writers John Flesher in Traverse City, Mich., and Barbara Rodriguez in Columbus, Ohio, contributed to this report.