The coldest November mornings on record have left local grape growers assessing varying degrees of damage from unseasonal frosts.

Reuben Corsini from La Cantina King Valley said while there hadn't been a complete wipe out at the family winery, some of the vineyards were looking "pretty ugly" at the moment.

He said the impact was widespread but patchy through the mid-King Valley region as a whole, with some vineyards spared and others damaged by the late spring frosts on the sub-zero mornings of 12 and 13 of November across much of the North East.

"Probably 60 per cent of the vineyard has been hit, and of that, the yield loss might vary from 100 per cent in some blocks to less than five per cent in others," he said.

"It's a bit of a waiting game."

Mr Corsini explained that as a cool climate vineyard, because it's so late in the growing season, even if the damage was stripped back, the vines would reshoot, but it was too late to get another crop.

He said while some varieties are impacted more than others, it's more about site damage within individual blocks in the lower lying areas where the frost settles.

"Once we get through flowering, we'll have a much better picture of how many bunches have been affected, but I expect losses through the broader North East Victorian region will be significant."

Mr Corsini said while an early October light frost might happen on occasion, later in November is extremely rare, and the family doesn't use frost protection because it's generally not a frost-prone site.

"It's tricky now from a management perspective because you've got some blocks where the bottom half of the row is affected, but the top half isn't, so you've got vines in the same row at two different growing stages," he said.

"But that's agriculture - you're at the mercy of the gods sometimes and they don't always play ball."

At Chrismont Wines in the upper King Valley, the affect of the frost was felt right across the Cheshunt vineyards, from the hills to the flats.

Vigneron Arnie Pizzini said the last time they experienced a frost like this, at roughly the same time in November, was in 2006.

"There will be crop reduction but as to what amount we don't know yet until flowering happens," he said.

"While some bunches you can see were burnt, we will wait to see if the bunches that are still there are viable or not.

"Over the next few weeks, we should be in a much better position to tell the extent of the losses."

Mr Pizzini said they have a couple of frost protection fans on the property and where they were in operation, they had worked very well.

He said the problem was not how cold the temperature got, but the length of time it remained cold, going down to zero early in the morning and staying there for some five hours.

He said his Whitfield vineyard fared much better, with some scorched leaves, but no crop losses.

At the other end of the valley in Milawa, frost protection in the form of automated impact sprinklers ensured the vineyards at Brown Brothers weren't affected by the cold weather event.

Brown Family Wine Group viticulture manager Victoria Sean Dean said without that frost protection, losses at the site would have been significant.

Mr Dean said the event did however affect about half of their grower base in the King Valley, who supply fruit to the company, and at this stage they are reporting losses of about five to 10 per cent.

"It was certainly an event, there were certainly some losses in the King Valley, but not likely to be higher than 10 per cent," he said.

"We're not out of the danger period yet but it is getting unlikely, in late November, that the valley would be affected by frost again."

Mr Dean said while there was no frost protection at their Banksdale Vineyard, its elevation made it significantly warmer than lower lying Milawa, and not as susceptible to frost.

He said while frosts can happen in November, it was certainly unusual to happen this late in the year.

With their dams mostly full, Mr Dean said a bit of rain now would be handy, and after what had been a cool spring, he was looking forward to the weather warming up and getting more canopy growth.

On the plus side, King Valley wineries across the board reported a very successful La Dolce Vita food a wine festival this year, despite experiencing wintery conditions on the second day of the event.

Mr Corsini said visitation numbers on Saturday at La Cantina were the best they'd had since COVID, and close to pre-COVID levels.

"We were really pleased - Saturday was fantastic, with a really good crowd, and the atmosphere was exceptional," he said.

Retired CSIRO climatologist Peter Nelson said Wangaratta shivered through its coldest ever recorded minimum temperature for the month on Wednesday, 12 November, dropping to minus 1.3 degrees, making it the coldest morning in 68 years of records.

The following Thursday morning it went down to minus 0.8 degrees, the second coldest ever morning on record, with light frosts on both mornings.

Mr Nelson said pairs of very cold mornings in Wangaratta during November are very rare.