Wine grape growers in some of Australia’s largest and most iconic regions say they have suffered crop losses due to unseasonable frosts, which are forecast to continue.

Overnight freezing temperatures have hit large parts of the country in recent days, with the Barossa Valley, Clare Valley and Riverland just some of the regions affected.

Temperatures dipped as low as -4 degrees Celsius in the Barossa on Monday morning and 1.5C in the Riverland. 

It follows a string of cold nights and early mornings, with temperatures dropping into the low single digits and below zero in both regions.

Wine grapes damaged by frost in Monash, South Australia. (ABC News: William Hunter)

Fifth-generation grape grower Adrian Hoffman, who is based in the Barossa Valley, said it was hard to estimate exactly how much crop he had lost in recent days.

“It’s been quite devastating, considering we’ve got quite a bit of frost mitigation [strategy in place] and we’ve been frosted quite severely under frost fans,” he said. 

“Generally once [the temperature] gets down that low, the damage is quite extensive.

“In our experience, once you’re impacted more than 50 per cent you’re likely better off just cutting the crop back.”

Constant vigilance

In the Riverland, which is Australia’s largest wine grape growing region, Michael Spivahtaris has already started counting his losses at his vineyard in Monash.

He said at least 20 per cent of his crop had been destroyed by the string of September frosts, which were caused by low winter rainfall.

Michael Spivahtaris says recent frost events in the Riverland has damaged 20 per cent of his crops. (ABC News: William Hunter)

The Riverland has an annual average rainfall of 250-300 millimetres but received only 50mm in the past three months.

“Unfortunately, it hasn’t rained, it is very dry and we’re going to be susceptible to frosts right up until the end of October unless we get some very good rain within the next week or so,” Mr Spivahtaris said.

“Wherever the frost has hit our crops, it has taken those vines out for the rest of the season. It isn’t a good scenario.”

While frosts have caused Mr Spivahtaris stress, he said it would be felt by more industries further afield. 

“If you’re in an area where the frost came through, any sorts of crops can be damaged: almonds, stone fruit, apricots or peaches,” he said. 

Michael Spivahtaris has been harvesting in the same region for more than four decades. (ABC News: William Hunter)

Early budburst challenges

Clare Valley Matriarch & Rogue owner Marnie Roberts said an earlier budburst had put growers in a “danger zone”.

“With an early budburst we have an extended length of time under that frost pressure,” she said. 

“It is really quite frightening for producers around the place.”

The Clare Valley is a region famed for its riesling, shiraz and cabernet sauvignon grapes

Marnie Roberts is a winegrape grower based in the Clare Valley. (Supplied: Marnie Roberts)

Ms Roberts said while growers in her region were impacted differently, the whole industry would be working hard to reduce the impacts of frosts, which were forecast to continue. 

“There are a lot of growers out there madly slashing underneath the vines so the frost doesn’t settle on the vine itself,” she said.

“Liquid nitrogen is being used to stimulate growth in the roots.

“We just need a bit more sunshine and warmth, a little bit of cloud, rain and wind to move the cold air away.”