RICHMOND—Wine grapes typically fare well in hot, dry weather, but this summer’s prolonged drought conditions have given Virginia growers cause for concern.

Record temperatures in June and July have caused some grape varieties to ripen earlier than usual. "We are seeing the earliest harvesting of grapes in Virginia in memory," said Virginia Tech viticulturist Tony Wolf. "Central Virginia vineyards were harvesting some grapes for sparkling wine, as well as pinot gris, in early August."

Extended dry conditions, or drought stress, "can lead to reduced yields and altered grape composition at harvest," Wolf said. "Wines produced from drought-stressed grapes are often unbalanced, may lack color intensity in reds and may not age well."

Many vineyard operators irrigate their grapes, but "the heat effect on grapes is much more difficult to deal with," Wolf added.

Sales of Virginia wines in 2009 increased more than 7 percent over those of 2008. Virginia is the nation’s fifth-ranked state for wine production, with cash receipts of more than $10 million for wine grapes last year.