The Transport Agency is warning motorists to continue to take care after what is likely the most widespread frost for the South Island this year.
The agency warned people to take care on the roads last night as temperatures were expected to drop to their coldest so far this year.
Spokesperson John Jarvis said inland areas of Otago and Southland were as cold as expected] and grit was being used on the roads to manage ice.
He said he had not heard of any major crashes overnight, but it was still very cold with road temperatures near Queenstown getting down to -7°C.
"The morning's not over yet, but I'm not sure of any major issues out there.
"We're still advising motorists to take care."
He said temperatures were expected to remain cold, and wet weather was also on the way.
MetService meteorologist Stephen Glassey said temperatures around the South Island got very cold overnight.
"There was frost over just about the entire South Island, but also in the North Island.
"In terms of widespread frosts it would be one of the coldest, probably the coldest we've had all year."
He said Mount Cook recorded temperatures of -10° this morning, with -8° at Tekapo and -7.4° at Pukaki.
"I would say some of those probably would have been the coldest."
The North Island escaped some of the freezing temperatures however.
"Over the upper North Island there was actually a bit of rain, so they had a bit cloud cover.
"Most places in the South Island were colder this morning than yesterday morning, in the North Island it was colder yesterday because of that cloud cover and stuff moving over."