Viticulture consultant Gary Crabbe described the effects of the cold snap on Gibbston vineyards above 380m as " a severe setback".
"With the heat on the vines today (Monday) you can see the full impact with shoots turning brown and it's pretty serious in places."
Icy winds on Saturday did the damage, rather than temperatures well below zero, he said.
"Helicopters, wind machines, diesel pots - none of them worked, which made it a rare occasion. Water by the bucket-load would have been the only thing that saved them, but those vineyards don't have access to water in those volumes.
"Growers are saying we've never had a spring frost like it - it was an exceptional one and there's a lot of head-scratching going on. Nature was certainly cruel."
However, it was important to note that Gibbston made up only 15% of the Otago grape-growing area, and less than half the Gibbston vineyards - maybe 10 or so - were affected, Mr Crabbe said.
There was still a chance of a crop from the damaged vines, as new shoots could replace the frosted ones. The crop would be later-maturing and smaller, but it would mean the crop was not completely "wiped out".
Damaged leaf tissue and shoots were being removed but the real impact of several days of cold weather would not be known until about Christmas time, when the effect on the grape flowers was known.
Central Otago Winegrowers Association president James Dicey, of Bannockburn, said most of the grape-growing district received only a "mild tickle-up" of frost, although vines in parts of the region never frosted before sustained some damage this time.
The deputy chairman of New Zealand Winegrowers, Steve Green, of Carrick vineyard, Bannockburn, said the district had got off lightly, overall.
"The season is looking pretty good, right around the country.
All the growers have had a nice start to the season, with good spring weather," Mr Green said.
Summerfruit New Zealand chairman Gary Bennetts, of Roxburgh, said the frost alarms went off on Saturday morning but he believed fruitgrowers throughout Central Otago fared "OK" during the cold spell.
"That said, there's different microclimates everywhere - sometimes the hills get frosted and sometimes it's the turn of the valleys, so there's no set pattern."
