Enjoy the spring sunshine today before a blast of cold Antarctic air brings three days of rain, icy winds and even snow to some places.

MetService meteorologist Matthew Ford said a belt of high pressure remained over the country today, keeping the weather relatively settled for most.

The North Island was in for a day of temperatures mostly in the late teens, with plenty of sunshine and just the odd shower, mostly about the ranges.

Very similar conditions were forecast in the South Island, with even Dunedin forecast to crack 18C.

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But don't get used to it, because by tonight it will all begin to change.

A significant cold front was arriving in Fiordland tonight, bringing bitterly cold strong winds, heavy rain and possible heavy snow to some parts of the country over the next few days.

"The second half of the week is really not looking too good," Ford said.

On Wednesday the rain would spread across the whole South Island, heaviest in the west, with temperatures plummeting and bringing snow to 400m in some areas.

By Thursday the system would make its way on to the North Island, bringing heavy rain to central and northern New Zealand into Friday.

A low was also forecast to develop along the front on Thursday which would track east across the North Island on Friday.

Periods of heavy rain were forecast about the ranges of Buller and Nelson, and the Richmond Range late Thursday and early Friday.

There was also a chance of heavy rain about Mt Taranaki, the Whanganui headwaters, Tongariro National Park, and eastern Bay of Plenty.

Heavy snow could fall above 400 metres about inland parts of Otago, Canterbury, Marlborough and Nelson through to Friday.

In the North Island there was a chance of snow down to 600m about the central North Island high country, with higher roads in this area likely to be affected including the Desert Rd.

As the front and low moved away to the east on Friday, strong, cold south to southeasterly winds were expected for many places.

On Saturday there was a chance of heavy rain for Wairoa and south of Gisborne, but with freezing levels expected to lift by then the chance of heavy snowfall in the area was minimal.

Today's weather

Whangārei

Long fine spells, chance of a shower or two. Light winds. 18C high, 9C overnight.

Auckland

​ Long fine spells. Light winds. 17C high, 10C overnight.

Hamilton

Long fine spells. Westerly breezes. 17C high, 6C overnight.

Tauranga

Showers clearing and becoming fine by afternoon. Light winds. 19C high, 7C overnight.

New Plymouth Mainly fine. Westerlies. 16C high, 9C overnight.

Napier Mainly fine with light winds. 18C high, 7C overnight.

Whanganui​ Fine, apart from morning and evening cloud. Westerlies. 17C high, 9C overnight.

Wellington Fine spells. Chance shower until evening. Northerly strengthening. 16C high, 10C overnight.

Nelson Morning cloud then fine. Light winds and sea breezes. 16C high, 7C overnight.

Christchurch Fine apart from some morning cloud. Northeast developing afternoon, turning northwest evening. 17C high, 6C overnight.

Dunedin Fine. Cloud increasing evening. Northeasterlies developing afternoon. 18C high, 9C overnight.