Part of the South Island is on standby for flooding as the area will get pummeled by heavy rain, while central and upper North Island won't escape the wild weather.
MetService said a "complex trough of low pressure" is expected to move onto New Zealand on Tuesday, which will bring an extended period of significant heavy rain and severe northeast gales for parts of the country.
A heavy rain warning is in place for the Westland, Buller and Tasman districts, with three days of wild weather expected.
MetService said the heavy rain may cause streams and rivers to rise rapidly, while surface flooding and slips are also possible and driving conditions may be hazardous.
WeatherWatch is warning of a "significant rain event" for Nelson and Tasman areas, while incredibly, MetService said nearly a metre of rain could fall in the Tasman District west of Motueka.
"Expect 450 to 700 mm of rain to accumulate about the ranges, and 180 to 280 mm about low lying areas. Some models indicate 700 to 800mm about the ranges during this period," MetService warned.
The rest of the South Island is under a rain warning and could see up to 600mm over the next three days.
NIWA warned of a "long-lived atmospheric river" that will hit the South Island on Tuesday before intensifying on Wednesday and Thursday and lasting into the weekend.
"This will lead to flooding, slips and washouts with well over a month's worth of rain, especially in the northern & western South Island," NIWA said.
North Island
The North Island doesn't escape the bad weather, with wind and rain warnings in place for certain areas.
A heavy rain warning is in place for Mount Taranaki, which is expected to see up to 400mm of rain.
MetService said locals should be prepared for surface flooding and slips, while driving conditions may also be hazardous.
A heavy rain watch is in place for Waikato, Waitomo, Taumarunui, Taupo, Taihape, North Taranaki, Auckland, Great Barrier Island and Northland.
MetService said these areas could see periods of heavy rain, which could approach warning criteria.
A strong wind watch is also in place for Northland, Auckland and Great Barrier Island, with northeast winds potentially approaching severe gale in exposed places at times.
