The wintry blast that brought snow to high country areas of the South Island overnight is set to sweep up the country with gales and heavy rain.
Snow fell in high country areas of Otago and Southland overnight, closing roads.
MetService says snow fell down to 200m in Southland.
State Highway 94 between Te Anau and Milford is closed from Hollyford Road because of snow and a rising avalance risk, and is likely to remain closed until midday.
MetService forecaster Heath Gullery said the cold weather system wasn't over yet.
Heavy rain warnings and watches are in place for north west Nelson, the ranges of Buller and the Richmond Range.
Mr Gullery said Up to 100mm of rain could fall in north-west Nelson.
Gales of more than 90 km/h are also expected for the Kaikoura coast and in Wellington.
Yesterday, temperatures dropped rapidly as the front moved up the South Island.
Snow has turned the Te Anau area into a winter wonderland as a cold blast sweeps through, making the spring school holidays seem more like the winter break.
The MetService forecast for Fiordland and Southland has come to pass, with heavy rain and snow to 200 metres.
1 NEWS video shows near whiteout conditions, with snow flakes close to the camera and the ground blanketed on a rural property in the Te Anau area.
The Lake Te Anau waterfront is also white, and a picnic table looks uninviting.
But a dog on the waterfront is undeterred from having a run.
The cold snap is not over yet, MetService saying another cold change is expected to sweep out of the Southern Ocean and onto the South Island tomorrow night.
Rain and snow will clear in the deep south during this evening, but return tomorrow night.
Canterbury and Otago are not immune with snow down to 500 metres and rain easing in Otago this evening.
A wintry blast expected to hit the country later today could affect travellers on some South Island roads.
MetService is warning the cold front set to move over the lower South Island will bring snow to low levels.
Inland parts of Otago and south Canterbury are under a heavy snow watch with snow levels dropping to 400m, and snow is expected down to 200m for Fiordland and Southland today.
MetService issued snowfall warnings for several roads, including the Crown Range and Milford roads where snow showers are expected from mid-afternoon. On Lindis and Haast Pass light snow is expected later this evening.
The road to Milford Sound has been closed because of avalanche risk.
Heavy rain and low-level snow are forecast as a front moves north-east over Fiordland and Southland this morning.
State Highway 94 from Te Anau is likely be closed all of today at this stage.
The weather front producing the snow only reaches upper South Island at midnight, so the North Island is forecast to be mainly fine and dry today.
Heavy rain is due in the ranges of Buller and Nelson, and the Richmond Range tomorrow.
Later in the week the strong, cold south to southeasterly flow is expected to spread across the North Island, bringing high winds to parts of Wellington and coastal Marlborough, and possible snow above 600m in the central North Island high country and the ranges of Hawke's Bay.
The Desert Road and the Napier to Taupo Road are likely to be affected.
As we charge towards summer, don't expect sustained warm weather just yet.
"October's going to be on the cool side for much of the country," NIWA principal forecasting scientist Chris Brandolino told TVNZ1's Breakfast today. "So no sneak peeks of summer, it looks like - at least very limited."
And as we teeter on the edge of a possible El Niño, there's some discouraging news for farmers: October is looking to be quite dry as well.
"We've already started out pretty dry across much of the upper South Island, and that doesn't bode well because some people have actually started irrigating," Mr Brandolino said. "That's pretty unusual given that we're coming out of winter.
"The fact that we are starting off dry in some areas, and the fact that we're looking at dryness in the month of October - that could basically continue on."
Mr Brandolino emphasised that El Niño hasn't developed yet, and it may not this year. If it does develop, it's looking like it could be a weaker system than in years past, he said. We'll know for sure sometime between now and the end of the year, he predicted.
"Generally speaking, you can conjure up images of more rain than usual across the western part of both islands, and less rain than usual across the eastern part of both islands," he said of El Niño years. "That's not always the case. We know the average outcome of El Niño, but no El Niño is average."
Mr Brandolino compared El Niño to a hand on a steering wheel. Historically, that grip has been about 25 per cent.
"But because this El Niño, should it come to fruition, is expected to be on the weak side...it may not have that firm grip on the steering wheel," he said. "It may allow for other people to take the steering wheel.
"So there may be these episodes when the wind comes from the west, which is typical of El Niño, and then that stops. We get other influences, say from the north and northeast."
Those in the agricultural sector who rely on steady rainfall will be keenly watching along with NIWA staff to monitor the evolution of the potential weather influencer, he said.