Spring frosts may wipe out more than 20 per cent of Central Otago's wine harvest next year.
The area is the third-largest wine region in New Zealand, behind Marlborough and Hawke's Bay.
"It's too early to be sure but my conservative estimate is for a 20 per cent loss across the region, due to frost," says Central Otago viticulturist Grant Rolston.
The worst frosts this month caused devastating damage to grapevines in some parts of Central, but since flowering and fruit set have yet to occur, it's impossible to know how much damage resulted.
Viticulturist Max Marriott suggests the impact of the frosts may mean up to 30 per cent fewer grapes are harvested next year.
"It was a worse frost than usual and was particularly hard for some to combat," Marriott says. "Cold air moved rapidly through the region to produce the frost conditions and then the temperatures got colder a lot quicker than usual and stayed colder for longer."
The most treacherous part of the day was about 6am when temperatures were at their coldest.
The proof of how much pinot noir will be in the bottle will begin to be revealed early to mid-next month, once grapevines have flowered. This determines how many grapes are then able to form on the vine.
"By that stage we'll see what impact the frost really had, depending on how well the vines flower and then have fruit set," Rolston says.
The area along Wanaka Rd, the Pisa sub-region, was the worst affected, says Marriott.
Quantity is certain to be reduced but the impact of a frost on vines before they have flowered means that quality is not at all affected, says winemaker Steve Davies of Doctors Flat Vineyard.
He says this year's frost was unusual because there was very little inversion layer, which helps prevent frost settling.
Historically, Central Otago has been the fourth-largest wine region in New Zealand, behind Gisborne, but figures released this week by New Zealand Winegrowers show it now eclipses Gisborne. Central and northern Otago have 1787ha of grapes, 5 per cent of the country's vineyards, compared to Gisborne's 1617ha. The new data reflected the hectares of vineyards rather than grapes harvested.