The Austrian Eiswein and the Canadian equivalent, Icewine, are made when some of the grapes are left on the vine after the harvest in autumn and picked after the first winter freeze. The extreme cold means that much of the water in the grape is removed. This gives an extremely sugar-rich mixture when the grapes are pressed, thus making for a very sweet dessert wine.

But whereas Canada has had a very strong harvest, due to the deep freeze that crossed large swathes of North America, Austria’s winegrowers are warning that the extremely mild winter is threatening this year’s Eiswein harvest. This wine needs a temperature of between -10°C and -7°C. Unless things change very soon, the grapes left on the vine will start to rot.

Austrian Eiswein accounts for between one to three per cent of the country’s total wine production. Eiswein from the eastern province of Burgenland is regarded as one of the most highly prized in the world, and sells for a significant price.

Meanwhile, winemakers in the polar-like Niagara region of Ontario have reported ideal conditions for their 2013 Icewine harvest and stated that it has been one of the earliest harvests on record.

According to the executive director of the VQA Ontario wine authority, the province has registered a preliminary grape harvest of 6,814 tons, which represents the largest harvest in the history of the region.

Regulations for Icewine include that the grapes must be left to freeze naturally on the vine at below -8˚C. Grapes are harvested at night and pressed while still frozen.