Dunedin is experiencing hailstorms, crashes of thunder and flashes of lightning while heavy snow and rain warnings are in place for some areas of Otago and Southland as the weather worsens in the South.
A broad complex trough is expected to cover the country next week through to Thursday, with embedded low centres.
Metservice has issued a severe weather watch for Fiordland and coastal Otago.
"Cold southerlies are expected to affect the south of the South Island from this afternoon through to later Tuesday, bringing wintry conditions to the south of the South Island. "
Snow is predicted to fall as low as 400m with significant accumulation at 800m in inland Southland, Central Otago and Clutha.
The weather watch is also in place due to the possibility that rainfall accumulation may reach warning amounts for coastal Otago.
MetService meteorologist Andrew James said the change would be felt in the South Island today.
"A lot of cold and wintry weather is on the way down south," he said.
"Tonight, Queenstown and Wanaka are looking like they will get down to about 2degC, which is cold for this time of year."
"It's going to be a cold and showery week."
Outbreaks of rain and even hail are expected over much of the country during this period, with the more persistent rain setting in about eastern parts of the South
James warned that South Island motorists needed keep an eye on the forecast for roads like Arthur's Pass, Porters Pass, and Lindis Pass over coming days.
Metservice warned periods of snow were expected in the Lindis Pass, Crown Range Road and Milford Road.
Snow was expected about eastern parts of the South Island above 400 to 500 metres, and possibly about the North Island high country above 1000 metres.
Main centre forecasts today:
Auckland
Partly cloudy. Chance shower. Light winds. High 21C, 13C
Hamilton
Mostly cloudy with a shower or two, then rain from evening. Northwest breezes. High 21C, 10C
Tauranga
Partly cloudy. A shower or two from afternoon. Northwest breezes. High 21C, 12C
Wellington
Rain clearing in the morning to fine spells. Showers developing overnight. Fresh northwesterlies. High 18C, 8C
Christchurch
Cloudy periods and chance shower. Rain and strong, cold southerlies developing toward evening. High 21C, 4C
Dunedin
Showers, with possible thunderstorms and hail from the afternoon, easing evening. Cold, brisk southwesterlies from late morning. High 14C, 6C
Source: MetService
- additional reporting NZME.