A wet, windy and snowy start to the morning is expected as "a pretty nasty cold front" moves up the South Island and across the North Island.
Severe weather impacts are expected in Southern New Zealand where there will be "very strong and rather chilly southwest winds".
Snow had fallen in parts of the South Island on Tuesday.
Snowfall prompted MetService to issue ice or snow warnings for several highways earlier today, but by 9am conditions were easing and the forecaster has lifted some advisories.
The Milford Rd will remain closed tonight, with snow continuing to fall on the remote highway.
MetService said a further 20 to 30 centimetres is due to settle on the road by on Tuesday evening.
The NZTA said the road is expected to reopen at about 9am on Wednesday.
All other highways are open but there are warnings in place for SH85 Palmerston-Kyeburn and SH87 Outram-Kyeburn.
There is snow on the Crown Range Road and chains must be carried, the Queenstown Lakes District Council advises.
The Clutha District Council said there had been reports of logging trucks getting stuck in snow, and the Owaka Valley Road has been closed.
High country areas in West Otago had some snow on the ground but the roads were passable.
Hail could be seen falling in Waipara on Tuesday morning.
Temperatures were below zero in some places - Mid Dome in Southland was at -6.5C around 7.15am, the Crown Range Rd was -3.5C, and on Dunedin's Swampy Summit it was -2.4C.
SH93 CLINTON TO MATAURA, SOUTHLAND - SNOW - 6:10AM
— Waka Kotahi NZTA Otago & Southland (@WakaKotahiOS) May 17, 2021
Due to snowfall on the road, please SLOW DOWN, increase your following distance and drive to the conditions. An update will be provided by 9am. ^AL pic.twitter.com/NFr0hkfhMw
MetService last night updated its severe weather information to include a heavy snow warning for Fiordland and a heavy snow watch for inland Southland, Clutha and Central Otago (south of Roxburgh).
Queenstown's skifields received a dumping overnight, with 10cm at Coronet Peak 18cm at The Remarkables, NZ Ski's Libby Baron said.
MetService last night updated its severe weather information to include a heavy snow warning for Fiordland and a heavy snow watch for inland Southland, Clutha and Central Otago (south of Roxburgh).
In an update this morning the forecaster said the warning remained in place but the watch had been lifted, and while further snow showers were likely today, the threat of large accumulations had passed.
A strong wind watch remains in place for Coastal Southland, Clutha and Dunedin, where there could be southwest gales from 10am-9pm today.
Wind watches further north had also been lifted.
An NZ Transport Agency spokesman said State Highway 94 in Southland was closed from East Gate (Hollyford) to West Gate (Chasm) from 4.30pm yesterday, because up to 30cm of snow was forecast last night.
Road users should check with the NZTA to see how the region's roads were affected before setting off, because they could close quickly, he said.
The weather is expected to remain cold tomorrow as an unsettled southwest flow moves over New Zealand, but it was expected to ease on Thursday as a ridge of high pressure moved on to the country from the Tasman Sea.
Those planning to travel across the higher parts of the South Island should check the NZTA journey planner for any road closure updates, with a number of road snow warnings in place in Southland and the Central South Island.
North Island commuters might want to pack a rain jacket and umbrella, Hines said Tuesday morning is expected to be wet.
A band of rain is expected for most of the North Island this morning, with strong and gusty winds also expected.
Rain which is expected to cross the North Island today has a chance to turn heavy, with the chance it may turn into thunderstorms.
The wild weather is expected to calm later in the day but there may be brief showers.
"Most places are going to get a fairly breezy day," Hines said.
Commuters also might want to wear an extra layer or two, with strong wind warnings in place for several parts of the country.
"We are expecting the strongest wind to be in the eastern North Island, [with a] warning in place for the Tararua district and southern Hawkes Bay," Hines said.
A number of strong wind watches are also in place for the far southeast of the country, where a strong southwesterly wind is expected.
Although the temperatures haven't dropped that much, Hines said "it's gonna feel a bit cooler".
Cold weather is expected for the lower South Island while it is expected to be warmer in the upper North Island.
"The maximum temperatures don't look particularly frigid," Hines said.
Yesterday, a tornado swept through the Taranaki town of Waitara, damaging buildings and sending trampolines "flying about".
Taranaki Civil Defence Emergency Management said it had received reports of the twister and that fire crews had been dealing with the situation.
McFarlane Motors in Waitara was in the tornado's path and Brook Prentice said they'd lost parts of their roof flashing as the tornado swept through, and pieces of their neighbour's roof had ended up on top of their workshop.
- Additional reporting Otago Daily Times