Westland is likely to get hit with 100 to 150 millimetres of rain about the ranges north of the glaciers, and 200 to 300mm of rain about the ranges further south.
Those who are nearer the coast can expect 70 to 140mm, with the largest amounts to fall about and south of the glaciers, and peak rates of 15 to 25mm/h about the ranges.
Those in Fiordland can expect 300 to 400mm of rain, with the largest amounts to fall about the fiords, and peak rates of 15 to 25mm/h. MetService noted these rainfall amounts are unusually large, even for Fiordland.
Streams and rivers are likely to rise rapidly and damage to trails and roads is possible, so people should be prepared if travelling.
Thunderstorms are also possible alongside the rain.
Canterbury lakes and rivers south of Arthurs Pass can expect 180 to 220mm of rain about the main divide, and 90 to 110mm within 15 kilometres farther east.
Otago lakes and rivers should expect 150 to 200mm of rain about the main divide, and 90 to 120mm within 15km farther east.
Buller and Westland about and north of Ōtira are under heavy rain watches, with rainfall amounts possibly approaching warning criteria.
A strong wind watch is also in place for Queenstown Lakes, Central Otago, Fiordland, Southland, Stewart Island and Clutha.
MetService warned northwest winds may approach severe gale strength in exposed places.
Further north, the showers will continue. Nelson is likely to develop scattered showers tomorrow evening.
Manawatū and Horowhenua may have isolated showers in areas of higher ground.
The remainder of the North Island will be mostly fine, apart from isolated showers in Northland this afternoon.
