Cyclone Debbie has started to hammer the central North Island, forcing a school evacuation and road closures in Taranaki.
Central New Zealand is on high alert as the country braces for a deluge so intense some areas will get three times April's normal rainfall in just 48 hours.
Virtually no region in the North Island will escape the potentially damaging torrential rain. It will also affect districts in the northeast of the South Island.
The Waitotara River in South Taranaki is already rapidly rising, Ngamatapouri School has been closed and evacuated, and Waitotara Valley Road is closed.
Farmers in low lying areas nearby are being warned to be prepared to move stock to higher ground.
Locals are being told to keep survival items and a getaway kit nearby.
South Taranaki District Council, Taranaki Regional Council, and Taranaki Civil Defence are all monitoring the system, and say they'll keep locals informed.
High tide is expected at 4pm today, with more heavy rain forecast for Taranaki's eastern hill country tonight
MetService has issued a swathe of rain and wind warnings that span the North Island and top of the south.
Civil Defence in regions throughout the country are closely monitoring the developing storm, which threatens to bring widespread flooding.
Taranaki, Whanganui, Hawke's Bay and the Tararua Ranges would be the first to experience the worst rain. All districts were under heavy rain warnings with up to 400mm expected in parts over the next 48 hours. Downpours were expected to become very heavy today.
The MetService warned these areas would experience intense rain for the next day and a half.
People are being warned to keep an eye out for potential flooding and slips.
Severe gales are also expected to lash southern Taranaki through to Buller from today and overnight.
This morning the MetService rain radar showed the storm making landfall and widespread torrential rain falling across western regions of the lower North Island. Already up to 70mm of rain had been recorded across central districts in the past 12 hours.
Niwa says the remnants of Tropical Cyclone Debbie are threatening to develop into a serious situation in the next 72 hours.
Tropical downpours are set to saturate Northland and Auckland tonight and Wellington will be drenched by heavy falls tomorrow.
Astounding levels of rain are forecast to saturate the North Island: 125mm is to fall in Northland, Taranaki and the central plateau by tonight.
In the latest MetService warnings, Whanganui is expected to get 250mm of rain in 33 hours from this morning.
"This is a significant amount of rain for these areas and people are advised to watch out for rapidly rising rivers and streams, and possible surface flooding and slips," said the MetService.
Regions from Coromandel to Nelson have been placed on a watch, and heavy rain is likely to reach warning levels by tonight.
Niwa forecaster Ben Noll warns deluge will be so bad it may drop up to three times the month's normal rainfall n just three days.
The MetService said the worst weather will hit today and tomorrow with heavy falls across central New Zealand. There would also be strong southeasterly winds that could turn into destructive gales.
WeatherWatch said central regions around or near Cook Strait, and those facing towards the Tasman Sea such as Nelson and Taranaki, were most at risk of flooding.
The Ministry of Education is advising parents to stay in touch with schools and early childhood services.
