Police are urging care on southern roads this morning, owing to icy conditions.
Roads were frosty and icy across the region, particularly in Dunedin's hill suburbs, police said.
Motorists were urged to delay travel if possible, and drive to the conditions.
The icy start has prompted a delay for several schools around the city.
All primary and intermediate schools, and DKA Dunedin Kindergartens from Mosgiel to Port Chalmers and to Waikouaiti are starting at 10am. Otago Polytechnic is also starting at 10am.
MetService showed that the temperature at Dunedin Airport was -6degC at 7am, making it one of the coldest places in the country. It was -6.3degC at Alexandra, and a bone-chilling -10degC at Tara Hills near the Lindis Pass.
This comes after the shortest day of the year made for a very long morning indeed for at least five Dunedin drivers yesterday, as icy conditions led to a spate of crashes.
Police urged caution on Dunedin roads yesterday after a series of minor crashes around the city before noon, including three on the Northern Motorway.
A police spokeswoman said ice had resulted in dangerous driving conditions.
However, no-one was injured in the crashes.
There were two similar crashes in quick succession in separate incidents of a car hitting a bank on the Northern Motorway, near Leith Valley, after 7.40am.
Another crash happened on the Northern Motorway after a driver lost control after hitting ice near Mt Cargill.
On Otago Peninsula, in Highcliff Rd, a vehicle hit a bank, reducing traffic to one lane.
Later in the morning, about 11.30am, a member of the public called emergency services after watching a ute slide on black ice in North Rd near Upper Junction Rd.
A police spokeswoman said the driver, and sole occupant, managed to get out of the vehicle uninjured after it slid around 20m down a bank.
Meanwhile, a collision between two vehicles caused one lane of the Southern Motorway to be blocked this afternoon.
A police spokeswoman said officers were notified of the incident in Caversham Valley Rd about 3.35pm.
When police arrived, all occupants were out of the vehicles.
The left-hand lane was blocked by the crash, the spokeswoman said.
Council transport delivery manager Ben Hogan said contractors patrolled overnight and treated some local arterial roads with either grit or the de-icing agent calcium magnesium acetate to lessen the effects of ice and frost yesterday.
However, sometimes roads could be clear all night and then icy later in the morning, as was the case yesterday.
It was also important to note that not all streets were treated.
Main arterial routes were the priority, followed by busy roads that fed on to arterial routes.
"While treating the roads helps to reduce risk, drivers still need to be particularly careful in winter months and not rely on this to remove the risk entirely."
Waka Kotahi NZ Transport Agency coastal Otago senior network manager Chris Harris said contractors treated State Highway1 with CMA, which was effective down to -7degC.
Following the application of CMA, patrols on the road determined grit was not required in addition to the de-icing agent.
Based on these assessments it was determined that the message boards in Palmerston, Waitati and Pine Hill did not require activation.
