Central Otago will experience the best of winter this week, with snow and brutally cold temperatures on the forecast. 

NIWA principal scientist Chris Brandolino says the "brutally, brutally cold" temperatures are coming from Antarctica, "right from the ice".

"It's coming right from deep in the polar region," Chris says

"The South Island's going to cop the worst of it."

Although ski fields in the South Island are set to get a good covering of snow, the forecast has brought a warning for farmers to protect their stock.

"The windchills are going to be brutally, brutally cold. By sunset tonight windchill for the South Island, the lower third of the South Island, [will be] -10C, -5C, -15C.

"This time tomorrow for the South Island, the windchill factor - the feel temperature - is going to be -15C, -10C, maybe -20C," Chris says.

Central Otago will experience a dramatic drop in temperature mid-week. Photo: MetService. 

According to WeatherWatch, the air will "progressively get colder" on Monday in the southern part of the country before "marching northwards over the rest of New Zealand tonight and across Tuesday".

"The colder the air is, the drier the air is - so snow and rainfall accumulation isn't overly excessive for most but clearly Southland and Otago will have the heaviest snow falls, above 100 or 200m (and heaviest above 400m) with 30 to 40cm possible. Central Plateau will get several centimetres of snow," WeatherWatch warned today.

Central Otago farmers are warned to look after livestock with temperatures set to plummet. Photo: Weatherwatch. 

The news is that scattered snow showers are forecast for this afternoon and evening, some possibly heavy, while it will remain cold with gusty southwesterlies.

Tomorrow is forecast to include scattered snow showers, clearing by afternoon to partly cloudy weather with gusty southwesterlies, easing later in the afternoon.

On Wednesday things start to even out, with a partly cloudy forecast to include morning frosts and light winds.

The cold snap will last a few days, before next month brings more variable weather.

"We see more variability for the month of July - so a lot more ups and downs - but there's certainly not going to be any sustained cold weather," Brandolino said.

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