Cold temperatures, icy winds and snow is expected in the coming days as a nasty low moves over the country bringing undesirable conditions to most areas.
MetService was keeping its eye on a cold outbreak as southerly changes pushed up from the Southern Ocean bringing turbulent weather with it, MetService meteorologist Andy Best said.
"The trough moves over central New Zealand by midday Monday, then over the upper North Island Monday evening. Strong, cold southerly winds will follow in the wake of the trough."
The cold air would spread over the east of the South Island today.
Paired with moist air, parts of the south including Southland, parts of Fiordland, Otago, Canterbury and Marlborough will likely get a drop of snow.
A low-pressure system would move east of the North Island from later today, spreading strong and cold south to southwest winds over areas south of Auckland, including the capital.
"During Monday morning and afternoon gale southerlies are expected to develop along the South Island east coast, with severe gales expected about Wellington and the Marlborough Coast and Sounds from Monday evening and a warning is now in force."
Many North Island places would struggle to reach the low teen's during the day, with 10C the maximum in Wellington from Tuesday to Thursday and 13C for Napier, Best said.
"People should layer up clothing-wise and be prepared for deteriorating weather conditions."
Slips are already coming down as Wellington braces for galeforce winds and heavy downpours.
The MetService has issued a strong wind warning and a heavy rain warning for the region.
From midday a period of persistent rain with heavy falls is forecast.
Later in the afternoon southerlies are expected to rise to gale force gusting as strong as 120kmh in exposed places through into the night.
Metservice meteorologist Lisa Murray said the wind and rain would continue until tomorrow morning.
"So quite a blast of southerlies some really cool temperatures over the next few days. Maximum temperatures are really just getting past 10 maybe 11 degrees."
A slip has already fallen onto the front of a car on Ohiro Road in Brooklyn.
Wellington City Council said contractors were on route to the incident and traffic management has been auctioned.
Another slip came down on the westbound lane of State Highway 58 earlier this morning, but has since been partially cleared.
A council spokeswoman said people should make sure their gutters are clear and trampolines are tied down.
From Northland to Taranaki and across to Taupō and Bay of Plenty, there was a moderate risk of thunderstorms developing from about dawn.
"A lower risk of thunderstorms extends to most remaining areas of the North Island north of Wellington and to western Nelson and Buller in the northwest of the South Island," Best said.
The forecast was not unexpected as the transition from winter to spring often brought turbulent weather, Best said.
"Seas are still relatively cold around Aotearoa, but as the subtropics start heating up quickly and temperatures remain cold to the south us, the thermal contrast can result in strong spring winds.
"We can also still experience very cold outbreaks, as southerly changes push up the country from the Southern Ocean."
Road snowfall warnings are in place for Desert Road (SH1), Lewis Pass (SH7), Arthur's Pass (SH73), Porters Pass (SH73), Haast Pass (SH6), Lindis Pass (SH8), Crown Range Road and the Dunedin to Waitati Highway (SH1).
As a southerly change bullies its way northward tomorrow, some rough seas are expected in the Cook Strait.