South Island motorists have been urged to take "extreme care" as a chilly southwesterly flow swept over the country, dropping temperatures and bringing snow to alpine passes.
The southwesterly flow has also brought unsettled skies further north, with a funnel cloud seen in southern Taranaki.
New Zealand Transport Agency Waka Kotahi said part of State Highway 73 between Christchurch and the West Coast was closed earlier due to the snow.
The section between Springfield and Arthurs Pass Village, including Porters Pass, was closed just before 4am, and reopened about 5.20am.
"While 'winter' driving conditions also persist in other parts of the South Island today, including State Highway 1 Dunedin to Waitati, there are no current state highway closures in the South," an NZTA spokesperson said.
MetService had on road snowfall warning still in place for Desert Rd in the North Island.
The forecaster said snow showers would clear slowly this morning, and another 1cm could accumulate above about 700 metres.
It said the southwesterly flow had brought a cold and frosty start to some, with Ashburton the coldest spot at 0C at 7am, while Wānaka and Milford Sound sat at 1C.
Scattered showers were expected to continue before easing from this afternoon.
Funnel cloud off Taranaki
Photos sent to 1News showed a funnel cloud off the south Taranaki coast near Opunake about 9am.
Marama Hohaia said it was already forming when she saw it during kura drop off.
"We watched it for about 30 seconds and it fizzled out again but was very loud then as we were driving home we had real heavy winds."
MetService forecaster Samkelo Magwala said a series of fronts was moving up the country, with a ridge of high pressure over the Tasman Sea creating the southwesterly flow.
"There's that possibility of some form of convective cloud," Magwala said.
"The atmospheric conditions are conducive. There's cold temperatures aloft, which are more consistent for the formation of such clouds."
MetService said yesterday that temperatures across the country were set to plunge, with Auckland forecast to drop to 4C on Thursday.
Frosts are expected across much of the country later this week, before the next weather system arrives on Friday.
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