Snow is falling on the Northern Motorway out of Dunedin this evening, prompting a call for motorists to take extreme care, or delay travel.
The warning, issued by the New Zealand Transport Agency around 8.35pm, came after snow had already forced the closure of some southern highways.
The NZTA advised that alpine road the Lewis Pass (Hanmer turnoff to Springs Junction), State Highway 94 - Te Anau To Milford Sound (from Hollyford and Chasm), State Highway 6 Haast Pass and SH 73 Arthur's Pass to Otira are closed tonight.
The other alpine passes in the South Island are forecast to get snow until tomorrow morning and Desert Road in the central North Island for much of the weekend.
The MetService said wintry showers about southern Fiordland would spread to Dunedin, Clutha and Southland today, with snow expected above 100-200m, but could reach near sea level in heavier showers near the south coast.
The NZTA said motorists should take extra care on South Island roads and chains were essential on many routes. People should check conditions before leaving home and drive accordingly.
Motorists should watch for ice and grit, particularly on shaded areas of roads. Black ice is forecast for the Southland region.
Canterbury/West Coast journey manager Lee Wright reminded drivers that chains are needed.
"If you see a sign saying "chains essential" that means you have to put them on. The current forecasts are for snow in the Canterbury high country down to 500 metres tonight. State highway contractors are all on alert and patrolling.
"The weather is not looking good for tonight and Saturday morning or Sunday night. Snow could be down to 200 metres."
Meanwhile, the showery southwesterlies also bring a risk of squally thunderstorms and hail to western parts of both islands.
"We're in for a changeable few days" MetService meteorologist Rob Kerr said today, "and further severe weather warnings or watches are likely to be issued as this situation evolves into the weekend".
Other highway conditions
SH75 - Banks Peninsula, Akaroa via Hilltop: expecting snow tonight.
SH6 - Franz Josef to Fox Glacier: winter driving conditions, be prepared.
SH8 - Omarama to Tarras: snow, chains essential, closed to towing vehicles.
SH80 - Mt Cook road: snow, chains are essential, closed to towing vehicles.
• For more road information go to the NZTA website.
