The first few days of August will bring cold temperatures, rain and windy conditions to much of the country.
Road snowfall warnings remain in place for a number of major roads in the central North Island and two cold fronts heading to New Zealand will bring wintry conditions over the next few days.
Niwa said high winds would cause at least 10m waves likely to impact the West Coast from today and into the weekend.
MetService meteorologist Stephen Glassey said a cold southwest flow was covering the country at the moment - bringing cold temperatures and windy conditions.
Overnight temperatures did not go down too much, as expected.
"But there were still a few places that were still below zero,'' he said.
Tekapo got down to -5C, while the Desert Rd got down to a chilly -3C overnight.
"There was snow there overnight and it could get some more this morning as well.''
Auckland got a lashing of heavy rain, growling thunder and lightning late last night.
Earlier yesterday, a hailstorm caused a bit of commotion in parts of the city when the huge amounts resulted in what almost looked snow.
Photos from Cockle Bay, Howick and Bombay showed roads covered in the snow-like hail and decks with a light dusting.
Showers are expected in a number of areas, including in Northland, in and around Auckland, Wellington and Christchurch. However, they are all expected to clear later today.
Aucklanders can expect occasional showers and southwesterly winds. A high of 13C and overnight low of 10C is expected.
But the MetService website said about 8am that it was feeling like 5C or "three clothing layers'' in the City of Sails this morning.
Whāngārei is in for some gusty winds today and a high of 14C. New Plymouth gets some fine spells but windy conditions too.
It will be a cold night in Palmerston North tonight, with an overnight low of 4C forecast. A high of 10C is expected and some light winds.
There will be the odd shower in Wellington - mainly about the eastern hills - but will clear by this evening. There will, however, be strong southerlies this morning.
"We've got a couple of active fronts that are moving across the country,'' Glassey said.
"It's going to be cold and windy over the next few days ... and there will be more snow down the bottom of the South Island and central North Island."
Two cold fronts are expected from today and then Saturday.
"It's going to bring showery and unsettled weather through to Monday.''
Despite the grim weather forecast, the fronts are said to be fast-moving and there will therefore be fine spells in the mix.
Those in Nelson, Buller and Westland are in for some fine weather most of the day, but showers are forecast later in the evening.
Marlborough and Canterbury are also mostly fine; save for showers in the Banks Peninsula and eastern Marlborough where there is snow.
Otago, Southland and Clutha can expect showers today. But things will clear out inland Otago by this afternoon and evening.
ROAD SNOWFALL WARNINGS:
Road snowfall warnings remain in place for Desert Rd (State Highway 1) and the Remutaka Hill Rd (SH2).
Snow showers are expected through to late this morning on the Desert Rd.
Between 2 to 4cm of snow may settle on the road above 800m and lesser amounts down to 600m, MetService said.
The same conditions are likely for Remutaka Hill Rd, with snow showers likely to fall near the summit through to early today.
The NZ Transport Agency Central North Island alerted motorists at 6.20am that overnight conditions had improved and that the Desert Rd remained open.
But road authorities warned people travelling there to stay alert still and to drive to the conditions.
"Please continue to take extra care on all roads around the Tongariro National Park and between Napier and Taupo, especially this morning," NZTA said.
There are no road snowfall warnings for Napier-Taupo Road (SH5), Lewis Pass, Arthur's Pass, Porters Pass, Haast Pass, Lindis Pass, Crown Range Road, Milford Road and the Dunedin to Waitati Highway.
Strong wind advisories are also in place for the Hauraki Gulf and Bream Head to Cape Colville.
Another strong wind advisory has been issued for the Manukau Harbour and Waitematā Harbour.