Cyclone Cook made landfall in Bay of Plenty, hit Hawke's Bay and is tracking down the east coast of the South Island.
It passed east of Wellington about 3am, Kaikoura at 6am, east of Banks Peninsula about 9am and east of Oamaru about noon.
It is weakening.
It's raining heavily in Christchurch.
More than 9000 residents in Hawke's Bay and about 1400 homes in Bay of Plenty are without power
Two people hospitalised in Hawke's Bay after a tree hit their car
Civil Defence asking people to remain inside and not go sight seeing in the morning
Thames, Coromandel and Bay of Plenty remain under states of emergency
Having battered the Bay of Plenty and Hawke's Bay, leaving homes flooded and without electricity, Cyclone Cook is still heading south.
Weatherwatch reports the ex-cyclone will "slink" southwards down the eastern side of the South Island today. As it moves southwards, expect a northwesterly airflow for the rest of New Zealand.
It's raining heavily in Canterbury and there's a report from Christchurch saying there are plenty of lights on at 4am.
That's not the case further north. More than 9000 residents in Hawke's Bay are without power as the weather system heads south after making landfall between Tauranga and Whakatane earlier tonight. About 1400 homes in the Bay of Plenty, including in Tauranga, also remain without electricity.
Emergency services received dozens of calls about homes flooding, along with powerlines and trees being brought down in the Thames-Coromandel District, Matamata, Tauranga and Whakatane.
Whakatane District Council says sections of the towns in the region remain without power and no fix is expected until later this morning.
Residents have been asked to conserve water.
Malcolm Davie said "enormous gusts like freight trains" have been hitting his house and farmland in Eskdale, 15 minutes north of Napier.
"It's an absolute howling gale here. Furniture's been blowing around, the power's been out for about two hours and there are trees down, round the area and on our property.
"We're really getting hammered. It's a lot worse than we thought - it seemed quiet earlier. We thought the forecast was for the Bay of Plenty and Whakatane but I guess it's moved down over the last two hours."
Coastal winds are picking up in the Wairarapa and Wellington regions.
Wellington southerlies will turn North-Westerly around 3-4am with a wind warning in place for the city with gusts up to 120km/hr expected.
The wind is also picking up in the Whanganui region. MetService meteorologist Brian Mercer says the area currently has strong winds gusting to around 65km/h, which will increase over the next few hours before dropping off overnight.
Police warned motorists that numerous roads across the region - "too many to name" - were closed due to trees.
They advised motorists only to travel if "absolutely essential".
In the suburb of Bayview, there is a diversion in place on Main North Road because of a substantial slip.
The Fire Service has declared its Multiple Incident Procedures in the region and all fire crews are currently out on jobs.
In Gisborne, power lines have fallen, trees uprooted and a shop window smashed by wind.
Rotorua is also being hit, with 400 homes without power.
Earlier, residents in Whakatane were stocking up on supplies at the local supermarket - after being told to have at least three days' supply of food and water - when the power was cut.
Wind gusts in the region reached over 100km/h.
Power was also out in surrounding areas, Waimana, Opotiki, Te Kaha, Ohope and Ohiwa Harbour.
In the western Bay of Plenty, more than 1400 homes were without power in Te Puke, Waihi, Matakana Island, Te Puna and Welcome Bay - where wind gusts reached 80km/h.
The Civil Defence Centre in Tauranga is using a back-up generator.
Air New Zealand cancelled flights in and out of Rotorua, Tauranga, Hamilton, Blenheim, Nelson and Napier and have warned of further disruptions.
MetService meteorologist Brian Mercer said Bay of Plenty residents may have felt the strongest winds around 7pm as gusts were also fueled by the relative high-speed of Cyclone Cook moving in a clockwise direction towards the North Island.
Multiple reports of trees down around the district. We won’t be able to deal with these until conditions ease.
— Whakatāne District Council (@WhakataneDC1) April 13, 2017
He said a cyclone is often strongest just before it makes landfall, and once over land it would lose some of its power.
While MetService anemometers have been knocked out in Whakatane, he said winds of 120km/h were now hitting Rotorua.
He said when Cook was a tropical cyclone and in the tropics over New Caledonia its power was fueled by the warm water and humidity. But once it entered the mid-latitudes it began to source its power from the upper jet steam winds.
The mid-latitude process, he said, often sees a cyclone "decay, then regenerate" as it moves away from the tropics.
Kevin Cowper, the Fire Service's Bay of Plenty coastal area manager, said earlier that emergency crews were "very busy" with flooding, slips, tree collapses, and downed power lines.
Extra personnel have been brought in, while "well-staffed" volunteer fire brigades were also being deployed.
Cowper urged those who were at risk of flooding to self-evacuate and seek higher ground.
The Ministry of Civil Defence and Emergency Management said people should have warm clothing, medication, important documents, and a clear emergency plan.
Civil Defence's Sarah Stuart-Black said in a press conference at 5pm people should be prepared for evacuations.
"We're not through the worst of this yet and even though the peak weather is hitting in the next three to four hours (7-8pm) some of the consequences of that won't be seen until tomorrow."
The atmospheric pressure ahead of Cyclone Cook is at similar levels to the storm which sank the Wahine 49 years ago.
At a Whakatane District Council Civil Defence briefing this afternoon, officials said during Cyclone Giselle in 1968, the pressure reached 968 millibars, whereas the pressure was at 970 today.
A typical range can vary between 970 to 1040 millibars, classing the current reading at the extreme lower end.
Chris Noble of MetService said the cyclone was on track to hit Wellington overnight and moving over the South Island and out to sea.
Bay of Plenty Civil Defence group controller, Clinton Naude, earlier said all residents living in low-lying coastal area were being advised to self-evacuate with significant swells and sea surges expected within the next 12 hours.
"These residents need to be watching for natural warning signs and if worried or in doubt - don't wait for official warnings, move to families and friends or another safe location on higher ground.
"Our advice is that it is best to do this now during daylight, and before conditions deteriorate further."
Bay of Plenty Regional Council duty flood manager Peter Blackwood said the force of the storm could be even worse than predicted, with high tide at 9pm and concerns of a wave surge.
Dams on the Rangitaiki River which breached its banks, evacuating the town of Edgecumbe last week, have been lowered ahead of tonight's deluge.
A spokesman for NZTA said five sections of State Highway were closed in Bay of Plenty and Coromandel.
MetService has throughout the day also advised people to consider altering their Easter travel plans.
A number of roads were closed in West Auckland as well as north of the city, in Wellsford and Warkworth due to flooding.
The Ministry of Education earlier closed 137 schools, with several more closing early.
The University of Auckland, Unitec, and AUT were all closed, as were many businesses in Bay of Plenty and Waikato including the Hamilton Zoo, the Rotorua District Court, and banks.
In Wellington, dozens of flights were either delayed or cancelled.
By tomorrow morning, the storm will be centred near Christchurch if current modelling is correct.
Downpours may be intense in South Canterbury and coastal Otago for a time tomorrow with concern of flooding.
A very different beast
Murray said Cyclone Cook had changed from a tropical cyclone to a "mid-latitude low" - a "very different beast" from Cyclone Debbie.
Debbie was spread out, and noticeable bands of rain hit the country interspersed with periods of calm. Cook, by contrast, will be short and sharp, but bring a "phenomenal" amount of rain, Murray said.
"It is a really tightly packed cyclone - the isobars are very tight - which means strong winds, heavy rain and storm surges."
Meteorologist Andy Best said he'd been working as a forecaster at MetService for about 20 years, and had never seen a storm like Cook.
He said the last one to have similar conditions was Cyclone Giselle, which hit New Zealand in 1968 and contributed to the Wahine disaster.
The sinking of the Lyttelton-Wellington ferry Wahine on April 10, 1968 was New Zealand's worst modern maritime disaster, claiming more than 52 lives.
The weather by region
Northland / Waikato • Heavy rain warnings in place. • Between 150-300mm of rain expected across Auckland, Waikato and the Bay of Plenty.
Auckland • Heavy downpours, flash flooding and 140km/h winds expected until midnight tonight. • Between 150-300mm of rain expected through to this evening. • Ferry and train services may have to be cancelled. • Possible vehicle restrictions on the Harbour Bridge because of high winds. • Auckland Council, Civil Defence and NZTA all urged care on roads. • Delays and cancellations expected on some train services. • Three Waiheke Island schools closed today.
Coromandel • Worst of the weather will hit today. Civil Defence emergency in force. • 150 to 250mm rain until midnight tonight, with intense rates up to 35mm an hour. • Winds of up to 150km/h or more possible from this afternoon. Peak waves of 5m or more on eastern coast. • Extreme care urged at high tide this morning (8.36am) and again at 9pm. High tide tomorrow at 9.16am and 9.41pm. Care should also be taken on the Firth of Thames coast. • Slips and flooding possible and could close roads. Easter holidaymakers urged to stay away.
Bay of Plenty / Edgecumbe • Up to 300mm expected in Bay of Plenty in next 48 hours. • Regional state of emergency in place as water pumped from flooded Edgecumbe. • Access to areas of Edgecumbe hit by last week's floods suspended because of the incoming weather. • 57 schools in the region closed, plus kura and early learning centres. • Edgecumbe residents will be alerted to evacuations with sirens from fire stations and emergency services vehicles.
Taupo • 150 to 205 mm through to midnight tonight. Wind gusts up to 150km/h or more possible from this afternoon until early tomorrow. • Lake Taupo could rise by half a metre.
Wellington • The storm expected to reach the capital early tomorrow morning. • It is likely to deliver heavy rain and strong winds.
Westland, Buller, Nelson • Intense rain forecast for region. • Up to 200mm of rain expected in ranges around Nelson, with maximum rainfall rates of 30 to 40mm an hour. • Slow-moving low from the Tasman Sea will bring rain to the West Coast before other regions in the South Island. • A severe weather watch has been issued for the affected areas.
Otago • Flooding fears for Dunedin. • Heaviest rainfall expected from midnight to 2am.