Snow and ice have closed roads across the South Island and ferry sailings between the islands have been halted as a polar blast storms up the country.
A number of main highways in Southland and Otago are closed after snow fell to low levels yesterday.
The bitter cold snap is bringing icy gales to many parts of New Zealand and monster swells are set to pound eastern coastlines.
Dunedin remains under a frigid white blanket and sleet and snow are expected to fall to 300m this morning.
Sections of state highways 85, 93, and 94 in the far south have been worst affected by the weather and motorists are warned to be wary of treacherous conditions on all southern and alpine roads.
Warnings have also been issued for snow on the Central Plateau though it is no longer expected to settle on the Desert Road.
All sailings on the Interislander ferries are cancelled as giant 6m swells are forecast to hit the Cook Strait.
Crossings may resume tomorrow, but new bookings are suspended until Friday.
Some Wellington harbour ferry services were cancelled this morning as sea conditions worsened.
The MetService said big swells were set to hit the east coast of the country and 5m waves are already pounding Christchurch. Models show waves higher than 7m - and possibly even 10m - will hammer beaches over the next 24 hours.
Those living along the southern Wellington coastline are being warned to expect big surges across roads and possible flooding at 8pm coinciding with high tide.
A strong wind warning is in force for Wairarapa, Hawke's Bay, the coastal parts of Southland, Clutha and Dunedin, Nelson, Banks Peninsula and the Port Hills of Christchurch.
Damaging gusts up to 120km/h were expected overnight in Wairarapa and Tararua, and in Hawke's Bay south of Hastings around dawn.
In the deep south, southwest gales are expected to hammer coastal areas between Bluff and Otago Peninsula, as well as Banks Peninsula, through to mid-morning.
A MetService forecaster said showers would continue across the country but conditions were set to improve throughout the day.
SOUTH ISLAND ROAD CLOSURES
• SH 87 Outram to Kyeburn
• SH 94 Hollyford Valley Rd to Gulliver River Bridge
The Wellington to Picton ferry had a technical issue and was being towed back to port.