Heavy rain and snow are on the way for parts of the South, including Dunedin, over the weekend.
MetService says a "complex low pressure system" is forecast to move on to New Zealand from the Tasman Sea this weekend before moving away early next week.
Snow is expected down to 300 to 400 metres across central and southern regions of the South Island, and heavy snow warnings have been issued for North Otago and South Canterbury, while a heavy snow watch is in force for North Canterbury and the remainder of Otago, including Dunedin.
Heavy rain watches are also in place for Dunedin and North Otago.
MetService said "significant" snow falls were expected above 500 metres in the South.
Southern road warnings
Issued by MetService at 11:47am on Friday
DUNEDIN NORTHERN MOTORWAY (SH1)
Between midday Saturday and 3am Sunday, expect 2 to 4cm of snow to settle on the road above 300 metres.
LINDIS PASS ((SH8)
Between 10am and midnight on Saturday, expect 8 to 12cm above 500 metres with lesser amounts down to 300 metres.
HAAST PASS (SH6)
Between 10am and 4pm on Saturday, expect 1 to 2cm of snow to settle near the summit of the road.
CROWN RANGE ROAD
Between 11am and 6pm on Saturday, expect 4 to 8cm of snow to settle on the road above 500 metres with lesser amounts down to 400 metres.
MILFORD ROAD (SH94)
Between 10am and 6pm on Saturday, 10 to 15cm of snow may settle on the road above 600 metres with lesser amounts down to 300 metres.
On Monday and Tuesday, the weather is expected to be unsettled.
There will likely be strong-to-gale force west-southwesterlies for coastal Southland and Otago on Tuesday.
The approaching low-pressure system was at the centre of differing views among weather experts this week.
The system was tipped to be associated with one of "the world's largest storms and would bring an Antarctic blast to the country", according to WeatherWatch.
Other weather experts - MetService and Niwa - suggested the storm was unlikely to even be near the country and that there was no reason for people to be alarmed as a result.
WeatherWatch has now backed down on its giant storm forecast - calling it not a storm, but an enormous low pressure system that will still alter the country's weather pattern.
In a forecast video for this weekend's weather, head analyst Philip Duncan smiled slightly as he acknowledged that "big Southern storm we've all heard about in the news".
He pointed out: "We never said that was coming directly into the country. We said, very clearly, it would influence our weather over the New Zealand area."
Pointing to the weather systems in front of him, he said: "And hey, guess what? These two [lows] are merging and there's a big southerly change coming in across the country on Monday."
MetService meteorologist Amy Rossiter said there had been some confusion among members of the public about which weather systems were affecting different parts of the country and when.
A low pressure system developing in the Tasman Sea would affect the central North Island - bringing wintry weather conditions - but would move away by early next week.
The low in the Southern Ocean, however, is expected to pass just south of the South Island and would affect areas on the south-east.
Although it would not pass directly over the country, it would bring colder temperatures and showery conditions, Rossiter said.
To add to the confusion, a cold front that extends from that Southern Ocean low may, however, move across parts of the South Island - again bringing wintry weather with it.
- additional reporting NZME
