Cyclone Gita is expected to move southeast across the upper South Island and the lower North Island late Tuesday and early Wednesday.
It is expected to bring swells of more than 8m, flooding and severe wind to many parts of New Zealand.
READ MORE: Latest region forecasts with NIWA update
It should then move further southeast away from the country on Wednesday.
People are advised to check the latest heavy rain and strong wind warnings and watches, to be well prepared.
"MetService have severe wind warnings for the upper two-thirds of the South Island and some western areas of the North Island," said senior meteorologist Lisa Murray.
"The rest of the North Island is on watch for potential severe winds Tuesday."
Northland: A strong wind watch is in place for six hours from 1pm Tuesday.
Northwesterlies may rise to severe gale in exposed places for a time.
Although not directly in line of the cyclone, low-lying Kaipara is in for strong winds.
Northerly 35-knot winds are expected late on Tuesday morning, then easing to northwest 20 knots Tuesday evening. A westerly swell rising to 5m can be expected for a time.
A high of 28C and a low of 19C is expected in Whangarei.
Auckland: Showers are expected to develop in the morning then periods of rain in the afternoon.
Like Northland, a strong wind watch is in place for six hours from 1pm Tuesday.
Northwesterlies may rise to severe gale in exposed places for a time.
A high of 28C and a low of 19C is expected.
Bay of Plenty: A strong wind watch has been issued, for seven hours from 7pm Tuesday to 2am Wednesday.
Northwest winds may rise to severe gale in exposed places for a time.
Coromandel: A strong wind watch is in place for six hours from 1pm Tuesday.
Northwesterlies may rise to severe gales in exposed places for a time.
Waikato: Scattered showers, with northwesterlies rising this morning to potentially severe gale this afternoon. Metservice has issued a severe wind watch from 1pm to 7pm today.
Gisborne and Hawke's Bay: A strong wind watch has been issued, for seven hours from 7pm Tuesday to 2am Wednesday.
Northwest winds may rise to severe gales in exposed places for a time.
Taranaki: Strong northerly winds will hit the Taranaki and Taihape regions.
Horowhenua/Kapiti/Wairarapa:
A heavy rain watch is in place for Horowhenua, the Tararua Range and Wairarapa for 15 hours from 1am to 4pm on Tuesday.
MetService said rainfall amounts may approach "warning criteria".
Manawatu/Whanganui: A strong wind watch is in place for eight hours from 7pm Tuesday.
Northwesterlies may rise to severe gale in exposed places.
Wellington: A strong wind watch is in place for eight hours from 7pm Tuesday.
Northwesterlies may rise to severe gale in exposed places.
Buller region/Nelson/Marlborough Sounds: This area is expected to be among the worst hit.
The strong winds could generate swells of up to 8m to the west of central New Zealand.
All schools in the region have been closed on Tuesday and Wednesday.
Canterbury/Otago: A heavy rain watch is in place for the Canterbury Plains including Christchurch and Banks Peninsula and also North Otago.
It is valid for 23 hours from 1pm Tuesday to noon Wednesday.
Rainfall amounts may approach "warning criteria".
Fiordland: A strong wind watch is in place for 12 hours from 3pm on Tuesday to 3am Wednesday.
Southeasterlies may rise to severe gale in exposed places for a time.
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