Icy conditions that caused major disruptions on some South Island highways this morning aren't expected to ease until early afternoon.
Bitter overnight cold in some areas resulted in widespread black ice which caught many drivers out, resulting in several crashes, especially in Canterbury, New Zealand Transport Agency Journey Manager Lee Wright said.
After a spell of relatively mild winters, this one had been especially harsh so far and driving conditions were very challenging, Ms Wright said.
A high-pressure system that brought an end to showery southerlies in Otago yesterday sent temperatures plummeting below 0degC in many places overnight, with Pukaki near Mt Cook clocking in at a bone-chilling -20degC.
Around Dunedin there was ice on some city roads, and several of the city's hill suburb primary schools had delayed starts this morning.
Buses services were affected but most are now operating as normal, the Otago Regional Council advises.
Roads
The New Zealand Transport Agency has issued a heavy ice warning for the Central Otago region, and advises of cautions on State Highway 94 Mossburn-Te Anau and Te Anau-Milford Sound, and SH8 the Lindis Pass.
- Check highway conditions here
The Queenstown Lakes District Council has also warned drivers of the conditions, saying the roads would be gritted but motorists needed to drive to winter conditions.
Extreme cold
The chill hit particularly hard near Mt Cook, with Pukaki recording a temperature of -20degC.
MetService Meteorologist Stephen Glassy said most of the South Island recorded sub-zero temperatures, including the -20degC at the Pukaki Aerodrome on the edge of Lake Pukaki.
The numbing figure was recorded early this morning.
The Niwa website says New Zealand's lowest recorded temperature is -25.6degC, in Ranfurly in 1903.
The wintry bite brought temperatures down to -5degC in Dunedin and Blenheim, -7degC in Queenstown and -3degC in Christchurch.
The cold conditions would stick around for the next few days, MetService said.
''It [the high-pressure system] will give some pretty decent days in terms of weather, but we're going to find our night-time temperatures really dropping away,'' communications meteorologist John Law said.
''Daytime temperatures will struggle as well, but I think the cold nights will be most noticeable,'' he said.
The high that moved in from the Tasman Sea to the southwest of New Zealand would linger through to Thursday, Mr Law said, ending snow showers that left ''a couple of centimetres here and there'' throughout Otago yesterday.
MetService meteorologist Frances Russell said Dunedin was expected to be fine until Thursday.
Combined with the low temperatures, that was the perfect recipe for ice, she said.
''If the roads are wet, [clear skies] will help the ice form,'' she said.
Ms Russell also warned there might be ''morning frosts [which] could be severe in places''.
Earlier report
A cocktail of ice and black ice caused several crashes in Dalefield and Speargrass Flat early yesterday.
Two more crashes occurred within a few minutes of each other in the afternoon.
Sergeant Mark Gill, of Queenstown, said no-one was injured when 11 vehicles slid off the road in a 90-minute period after 7.30am.
Five of the incidents were in Domain Rd, four in Littles Rd, and one each in Hunter and Malaghans Rds.
Two people escaped injury when their rental van rolled on the Crown Range road after hitting ice near the intersection with Jeffery Rd about 3.40pm.
The drivers of two vehicles that collided a few minutes later at Arrow Junction, at the intersection of State Highway 6 and McDonnell Rd, were also uninjured.
Sgt Gill said the crashes served as a reminder to motorists to drive to the conditions, particularly early in the morning on bends with speed advisory signs.
Black ice was re-forming on slippery roads around Queenstown about 4pm yesterday. Roads in that area are expected to be treacherous today.
Last night, the New Zealand Transport Agency had issued snow and/or ice warnings for several highways throughout Otago, including SH94 and SH8.
Dunedin police gave a sodden resident a ride home after their vehicle went off the road into Otago Harbour.
The incident happened at Deborah Bay about 9.45am yesterday. Police could not confirm whether an icy road was to blame.
The driver, the sole occupant, was able to get out before the car was submerged.
Southern District communications manager Nicholas Barkley said a passer-by stayed with the driver until police arrived.
In South Dunedin, two cars collided at the corner of Portsmouth Dr and Strathallan St. No-one was injured.
Dunedin bus services on eight different routes were suspended ''due to snow and ice on the roads'' yesterday morning. Another five were running on abbreviated or altered routes.
All buses were running normally last night, the Otago Regional Council reported.
About 9am yesterday, Queenstown Airport tweeted ''Flights on hold at the mo due to icy conditions & cold temps. Runway being continually assessed, we'll give the all clear as soon as we can.''
But Air New Zealand spokeswoman Alisha Lewis said last night there had been no cancellations of flights into or out of Queenstown yesterday.
A Dunedin Airport employee said there had been no weather-related flight delays or cancellations at the airport yesterday.
