A raft of heavy rain, strong winds and even snow is expected as a cold front begins to move across the country today
The deepening low is expected to move northeast across the South Island today, then over the North Island later tonight and early Tuesday.
It will bring strong winds and heavy rain while a strong cold southerly change is on the cards after it moves away.
MetService meteorologist Lewis Ferris said the South Island should expect an "abrupt change" in the weather today after a settled weekend.
"Most of the heavy rain will fall on the West Coast but a lot of it will also make it into southern and eastern regions.
"There is also some very strong winds and after all of that, we get the cold air coming in on a southerly wind which is also going to bring the snow risk down to about 400m to parts of the interior of the South Island."
The North Island will not be spared, he said, with periods of briefly heavy rain and strong winds expected on Tuesday.
A number of heavy rain, wind and snow warnings have been issued by MetService. Central and eastern parts of the North Island are in the firing line along with most of the South Island.
Snow is also expected for many parts of the South Island today with a smaller amount expected in the central North Island on Tuesday.
The Wellington Region Emergency Management Office is warning residents to beware of upcoming strong winds.
"Spring is that classic shoulder season where we see those periods of settled weather but also these fronts are never too far away and they can be quite fast-moving, that's what we've seen today," Ferris said.
He said most of the country should prepare for a "marked drop" in temperatures during the beginning of this week.
"Places around Southland and Central Otago were seeing temperatures in the 20C mark last week but this week, we'll struggle to see the temperatures get into the double digits."
Severe weather warnings
A heavy rain warning is in place for the Westland ranges, south of Otira and Fiordland.
From tonight and early tomorrow morning, heavy rain watches have been issued for the Bay of Plenty ranges, Tongariro National Park, Mt Taranaki and the Tararua Range.
In the South Island, watches are in place for Buller and Westland ranges, the headwaters of the Otago lakes and rivers, headwaters of the Canterbury lakes and rivers south of Arthur's Pass and the ranges of Tasman west of Motueka.
A strong wind warning is in place for the Marlborough Sounds, Wellington, and parts of Wairarapa.
Strong wind watches are in place for the Canterbury High Country, Banks Peninsula, Gisborne and Hawke's Bay, the Tararua District, Wairarapa north of Featherston, South Taranaki, Taihape, and Whanganui as well as coastal Buller and the rest of Marlborough.
Heavy snow watches are in place for the Canterbury High Country south of the Rangitata River, central Otago and the Queenstown Lakes District.