The NZ Transport Agency said while traffic was "light and flowing" on Auckland motorways, commuters needed to take care on the Northwestern Motorway due to the fog.
Kiwis woke to frosted windscreens this morning as overnight temperatures plummeted under a clear winter night's sky.
At about 5.30am Pukaki Airfield, near Twizel, was -7C and Dunedin Airport -6C.
MetService meteorologist Nick Zachar said almost the entire South Island was in the negatives this morning, apart from the West Coast which had a bit of a cloud and rain blanket.
Temperatures in the North Island were slightly warmer, but many areas still got close to 0C.
Even around Auckland some spots dropped to 2C.
Along with the cold temperatures a layer of fog had formed across the North Island, from South Auckland to Whanganui.
"It is pretty widespread, and goes across from New Plymouth to Napier," Zachar said.
A high pressure system forming over the country should lead to a fine day for most places, with just some on and off showers in Wellington and Kāpiti through the day.
The weekend was looking like a mixed bag, with mostly fine weather tomorrow before rain arrived Sunday.
Tomorrow was looking like the day of the weekend, Zachar said.
"Today's front will completely dissipate Saturday, and it is looking very good."
Mixed Weather This WeekendMixed Weather This Weekend
Tomorrow will see a calmer end to the week’s weather. Unfortunately, a system developing in the Tasman Sea will bring rain and wind to much of the country later this weekend and into the start of next week.
The video below shows the progression of the rain band as it passes down the New Zealand.
Saturday will be dry for most, but a few showers linger about the country. The rain band moves across late Saturday through Sunday, bringing wet and windy weather to the upper North Island and the west coast of the South Island.
With an event like this, it is important to stay up to date with the latest severe weather information at our website http://bit.ly/AllWarnings
You can also get the latest forecast for your area at our website http://bit.ly/metservicenz
^Tui
Posted by MetService New Zealand on Wednesday, 11 July 2018
It wouldn't last though, as a low coming across the Tasman Sea would start to spread a moist northeast flow over the country late Saturday.
The humid system would bump the winter temperatures up, but also bring with it some heavy rain to western areas from Sunday.
On Sunday northeast gales could be severe from Northland to Bay of Plenty and Taranaki. These gales would coincide with king tides, possibly affecting low-lying eastern areas.
There could also be heavy rain over Northland, Coromandel Peninsula, and parts of Auckland.
Later on Sunday and during Monday this heavy rain could spread to Bay of Plenty, parts of Nelson and Marlborough, and potentially Gisborne and over Fiordland and parts of Westland.
