While snow in the South Island was easing on Monday evening, MetService says a number of northern centres were still to receive their cold snap.
Forecaster Chris Noble says the coldest air was moving over the North Island on Monday night and causing heavy rain in Auckland.
Mr Noble says that rain could turn to snow, in particular on the hills surrounding Auckland.
But he says the cold was much more intense earlier in the day.
"Most of the snow is now moving off to the east of the country with the bulk of the cold air, but there is still a bit to come, to the central high country, and also around the eastern hills of Wellington and Wairarapa."
Mr Noble says all snow showers were expected to clear by dawn, the last of them from the Central Plateau.
Earlier, MetService said the snowfalls in the North Island were some of the worst experienced in recent years.
However, the Desert Road (State Highway 1), which was closed from Taihape to Rangipo; and the Napier - Taupo Road (State Highway 5) both reopened on Monday afternoon.
State Highway 2 from Napier to Gisborne remains closed, at Nuhaka. The Rimutaka Hill Road (State Highway 2) between Wellington and Wairarapa also remains closed, probably until Tuesday.
Transport Agency spokesperson Andy Knackstedt says crews are working to clear the roads, but snow was still falling heavily in some areas, meaning work is difficult.
Mr Knackstedt says motorists should drive very carefully, if they need to be out on the roads on Monday evening, as they are treacherous. He says some roads are unlikely to re-open on Monday.
AA spokesperson Simon Lambourne echoed this advice, saying drivers need to avoid heavy braking and quick acceleration on snow, icy roads.
He says, above all, people should not drive if they don't have to.
In Taranaki, police urged motorists to stay off roads around the southern side of Mt Taranaki-Egmont on Monday, as they were becoming impassable. They included those around Kaponga, Manaia and Kapuni; and Opunake Road between Stratford and Opunake.
South Taranaki District mayor Ross Dunlop says it is very rare to get snow in the valleys and lower country. He says the area is not geared up for it and working out how to care for stock is challenging for farmers.
At Taupo police say snow fell right down to the lake front.
Rare snow in lower North Island
Snow fell in the Wairarapa town of Greytown for the first time in many years.
MetService says snow there is a rare event. One resident told Radio New Zealand she thought it was the first snow in since 1909.
However, MetService says there are photographs of snow in the area in the 1940s.
Heugh Ackerley, in eastern Masterton, says in the 20 years he's lived there, it's the first time snow has fallen heavily.
Mr Ackerley says he's been told there was heavy snow like it in the 1930s.
Police say sleet and snow affected large parts of the Wellington region.
Snow falling with rain was reported in hillside suburbs of Upper Hutt, in Johnsonville, more thickly at the wind turbine above Brooklyn, and in Thorndon, almost at sealevel, among other areas.[image:2570:full] [image:2571:full]
Aucklanders have been looking to the skies to see if they're included in the winter blast.
NIWA is reporting the temperature and climate conditions are almost identical to when it was last reported to have snowed in Auckland, back in the 1970s.