Keep the fires banked and the stock sheltered — more snow down to 300m is forecast for Otago and Southland tomorrow.

MetService meteorologist Dan Corrigan said a trough was expected to move northwards across the country tomorrow afternoon and overnight into Wednesday, bringing cold southerlies which would deliver snow to some higher roads and passes around the regions.

"We are expecting snow down to around 400m in Dunedin late on Tuesday and that will drop a bit lower overnight into Wednesday morning, but we're expecting it to just stay up in the hill suburbs, unlike last week's event where it got right down to sea level.

Snowfall over next three days for lower South Island. Photo / snow-forecast.com

"For sure, we're expecting a good dusting on the hills with that southerly flick that comes through in the later part of Tuesday."

He said the situation would be similar for the entire southern region.

"The southerly change that arrives brings the heaviest snow-producing precipitation with it around midday in Southland, and will move up the country, arriving at Dunedin around 3pm."

Snow was expected to fall to 300m in Southland and Clutha, below 400m in Otago, and temperatures could drop as low as -3C on Wednesday.

Now that farmers were in the full swing of lambing and calving, he advised them to be well prepared again and move stock to sheltered areas in case the snow fell to lower than forecast.

"It's best to keep an eye on the forecast to see if any of the snow levels change and take any action to secure livestock."

Changeable weather was typical of spring, and fluctuations in temperature were expected, he said.

It was not uncommon to get warm, settled weather followed by cold outbreaks at this time of year.