Road snow warnings were in place through to tomorrow for Lewis Pass (State Highway 7), Arthur's Pass (SH73), Porters Pass (SH73), Haast Pass (SH6), Lindis Pass (SH8), Crown Range Rd, Milford Rd (SH94) and Dunedin to Waitati Highway (SH1).
Clydevale farmer and Federated Farmers Otago meat and wool chairman Simon McAtamney said many sheep farmers were in the middle of lambing but would be well prepared for the polar blast.
Farmers would be shifting stock to warmer paddocks and keeping an eye on their lambs to make sure they were kept warm, Mr McAtamney said.
High country farmers usually did not start lambing until the end of September, so were unlikely to be affected.
Cold blasts at this time of the year were just part of farming in Otago and Southland so farmers were well prepared.
"We get these spring storms and cold snaps — they're miserable days to work in but you just got to work through it."
The low weather system would surge over the remainder of the country heading into Tuesday, scaring spring out of the way for a week of winter weather.
Northland, Auckland, Coromandel Peninsula and the northern Waikato would be cloudy throughout the day before rain set in by the evening.
MetService meteorologist Ravi Kandula said slight warming could be expected heading into the weekend but the entire week would be cold.
"The cold air is going to be over the North Island by the end of Tuesday and sticks around through Wednesday and Thursday really.
"It's not going anywhere, a ridge does move over the country on Thursday but the cold air remains in place, largely through until Friday and Saturday," he said.
There was a chance snow would fall in the higher parts of the North Island like the Desert Rd as the cold front pushed northwards.
Western areas of the North Island would be wet today as brief rain gradually increased into showery weather.
Today's weather
Whangārei
Cloudy. A few showers from afternoon then evening rain, chance thunderstorms and hail. Easterlies. 18C high, 8C overnight.
Auckland
Cloudy periods, occasional showers from late morning, then evening rain, chance heavy with thunderstorms. Strong, gusty westerlies. 17C high, 9C overnight.
Hamilton
Occasional showers developing morning, turning to rain for a time in the evening. Westerlies. 16C high, 6C overnight.
Tauranga Cloud increasing. A few afternoon showers, then evening rain. Westerlies. 18C high, 8C overnight.
New Plymouth Occasional showers developing morning, turning to rain in the evening, chance thunderstorms. Westerlies. 15C high, 7C overnight.
Napier Fine, some morning and evening cloud. Northwesterlies. 19C high, 7C overnight.
Whanganui Occasional showers developing afternoon, turning to rain in the evening. Westerlies. 17C high, 7C overnight.
Wellington Showers developing morning, then rain at night as winds change from northerly to cool southerly. 15C high, 6C overnight.
Nelson Often cloudy. Rain for a time afternoon and evening. Southwesterlies. 15C high, 6C overnight.
Christchurch Rain, persistent from afternoon. Cold southeasterlies. 11C high, 5C overnight.
Dunedin Rain, persistent from late morning. Cold southerlies. 8C high, 4C overnight.
