The NZ Transport Agency Waka Kotahi (NZTA) said persistent freezing fog was likely for parts of State Highways 8 and 80 at least through until Sunday, along with hoar frosts and potential black ice on the roads.
The area between Twizel and Tekapo on State Highway 8 was expected to be especially high risk.
NZTA maintenance contract manager Chris Chambers said fog was likely to linger all day in some places.
"These types of conditions are not new for roads in the Mackenzie Basin area, but it is important that motorists take notice and adjust their driving for the conditions. Especially when there is an increased risk like this over a number of days," he said.
"We are expecting the freezing fog to hang around all day in places and there is a significant risk of black ice, especially in the mornings.
"All of this means increased risk of accidents and injury. It's important that drivers take extra care and slow down in these conditions, increase their following distances and drive with their lights on."
Contractors would be out checking roads and gritting or de-icing the affected highways over the coming days. However, Mr Chambers advised people to avoid travelling if possible.
"We have the option of closing sections of highway, or introducing restrictions, if the conditions warrant it. Our preference is to keep the roads open, and motorists can help us do that by driving with caution or staying off the roads if they can."
Central Otago and Queenstown
It's frosty in Central Otago this morning, with temperatures around -3°C dropping to a low of -7°C in the Maniototo at 6am. A spokeswoman for the district council said temperatures were likely to drop further on daybreak.
Though roads are dry, there would be patches of fog around Alexandra, Clyde and Earnscleugh areas today.
In Queenstown, grit has been applied to parts of Fernhill Rd and grit and fresh CMA have been applied to sections of the Crown Range Road linking Queenstown and Wānaka.
A spokesman for the Queenstown Lakes District Council said care was needed at the roundabout of Glenorchy Rd and Fernhill Rd. Grit has also been applied to roads on Queenstown Hill, especially Whakatipu Heights, Dublin St and Edinburgh Way.
"Ice is likely on Mount Aspiring Road so please drive with care.
"Given how cold it is, make sure you've got your chains in the boot, watch out for shady spots and bridge decks, and remember to slow down. Ice can form at any point."
- additional reporting ODT Online
