MetService has issued several weather watches and warnings across the motu as wind, rain and thunderstorms are forecasted to move in on Tuesday.
Both the North and South Islands are currently covered in watches and warnings on MetService's severe weather map.
Metrologist at MetService John Law told Newshub Tuesday will be the wettest and windiest day, warning the week "starts off pretty bad".
MetService has issued the Northland region with heavy rain and strong wind watches, with the heavy rain warning in place from 6am on Tuesday to midnight with possible thunderstorms. The region's strong wind watch comes into effect at 7pm on Tuesday and ends at midnight.
Law said it is "not just the fact it's rain, we've got some of these embedded thunderstorms too", with the "wildest" weather is expected to lash the top of the North Island, especially the western side of the country.
Moving further south, the Super City and the Coromandel Peninsula have been issued a seven-hour strong wind watch that comes into effect at 8pm Tuesday to 3am Wednesday.
The Bay of Plenty and Gisborne have also all been issued a 10-hour heavy wind watch from 8pm Tuesday to 6am Wednesday.
Bay of Plenty east of Opotiki, the ranges of Gisborne and north of Ruatoria have been issued a 16-hour heavy rain warning, with 90 to 140mm of rain expected to fall with the possibility of thunderstorms.
Its heavy rain warning comes into effect from 2pm Tuesday to 6am Wednesday, and Law said the warning will see the worst of the weather system.
The central North Island high country and North Taranaki has been issued with a heavy rain watch from 2pm Tuesday to 7am Wednesday.
Much of the west coast of the South Island is covered in yellow on MetService's severe weather map with a mixture of heavy rain and strong wind watches.
Canterbury high country has been issued with a strong wind watch from 8am Tuesday to 2pm.
Along the ranges of Westland south of Otira and Fiordland north of Doubtful Sound, MetService has issued a 12-hour heavy rain watch from 5am Tuesday to 5pm that evening.
Law said it's a very "active" start to the week and it's a "forecast to keep an eye on". He added by Wednesday afternoon Kiwis should notice a change in weather.
