South Islanders have been warned to expect snow on Tuesday as a polar blast arrives from the south.

The cold south to southwest airstream has a high chance of bringing snow in North Otago and Canterbury and a lower chance for North Canterbury, Central Otago and Southland, a MetService Severe Weather Outlook says.

Snow is likely to fall to very low levels, including the hills of Dunedin, it says.

"The heavy snow expected in the north of Otago and Canterbury has the potential to cause major disruption.

"People in these areas should prepare for difficult driving conditions, strong cold winds and a significant wind chill."

Though the risk of heavy snow is lower in Southland, it is likely to fall to low levels and cause stress to livestock.

Weather Watch analyst Richard Green says it could be the first in a series of cold southerly outbreaks as another surge of cold air is possible across the Far South on Thursday and Friday with Queenstown likely to have a mix of rain and snow.

Though conditions will be trying for many he says the snow is arriving at a good time for ski fields on the eve of the opening of the ski season.