Gale force winds and driving rain have caused road closures, power outages and slips around the country.
Flooding to the Coromandel - a popular holiday spot - has closed some roads, which will disrupt some holiday plans, police said.
The New Zealand Transport Agency (NZTA) is urging people to travel during daylight hours if they are going away for Easter. Slips and debris may be common on roads which will be dangerous at night.
Flooding along Auckland's Tamaki Drive and in eastern bays communities has subsided with outgoing tides.
Tamaki Drive has reopened and Civil Defence and other council staff were assessing the damage to about 11 properties which were impacted by the flooding.
Localised power outages were still affecting the region with about 17,000 properties still affected, Civil Defence said.
Contractors and emergency services continued work to clear fallen trees and other debris.
Flooding on Tamaki Drive in Auckland. Photo / Twitter / @FromAQuasar
Meanwhile, some roads were reopening on the Coromandel Peninsula after foul weather forced their closure throughout the day.
Senior Sergeant Rupert Friend said the Thames Coast Road was open, allowing access to Coromandel Town and Whitianga.
State Highway 25 between Waihi and Whangamata and Tairua and Whitianga had reopened.
But Tairua was cut off to the south and was expected to stay that way throughout the night, Mr Friend said.
The Pauanui access road was closed and with the tide still rising this would be for some time and possibly all night.
Kopu Hikaui Road was still closed and that would last well into the night, he said.
Tapu-Coroglen Road was now open, however it was not suitable for heavy vehicles to use.
"There are very significant traffic jams around SH2 / SH25 and around Kopu. Police urge patience as this backlog will take a long time to clear,'' Mr Friend said.
"Caution is urged on all coastal roads as the tide is coming in and high tide may well cause further road closures.''
Motorists were also asked to disregard messages on electronic signs at Thames because they were incorrect and were unable to be changed due to a technical issue.
A slip in Bay of Plenty has closed SH36 - the Tauranga Direct Road - police said.
Contractors at the site have told police the road was likely to be closed overnight.
Traffic at Te Matai has been diverted towards Te Puke on the Tauranga Side, and a Rotorua side diversion was being arranged at Dudley/SH36 and would be manned overnight by roading staff.
Motorists would have to divert back through Rotorua City to SH33 or via the Kaimai Ranges to get to Tauranga, police said.
"The best alternative is SH33 via Te Puke for both directions.''
Watch: Heavy rain and flooding hits Auckland
Ugly weather set to ease
The ugly weather that has crashed into the country today is due to ease over the Easter weekend, says MetService.
"Once the strong winds and heavy rain ease away, it will look far quieter and brighter. This should happen by Easter Sunday," MetService meteorologist Daniel Corbett said.
The intense band of rain and strong to severe gales will sink south to engulf central parts of the country by the end of today followed by slowly improving weather in the far north.
The rest of Easter weekend will bring a few passing troughs which could bring a bout of showers especially on the western coast, whereas eastern areas will stay mainly dry, Mr Corbett said.
Flooding on Tamaki Drive. Photo / Jarrod Wright
The storm also caused damage, power outages and disrupted travel across Auckland city.
By 2pm today, the fire service had responded to 770 emergency calls around the country related to weather.
Of those, 279 were in the Auckland region, 109 in Northland and 61 each in Waikato and Bay of Plenty.
See Vector's map of outages around Auckland here:
About 4500 Vector customers are still without power in the Auckland region, down from 15,000 at the storm's peak.
Power has now been restored to Campbells Bay, Alfriston, Greenhithe, Ellerslie, Dairy Flat, Waiatarua, Onetangi, Titirangi, Waimauku, Maraetai and Stanmore Bay, the company said.
Its crews are continuing to work on other outages around the Auckland region and will carry on this evening.
The outage manager, API, had taken 100,000 hits in the past 10 hours, Vector said.
In Auckland, extensive flooding up to waist height in places forced the closure of Tamaki Drive, from the Strand to Kohimarama Road, from 9am today.
Hectic conditions @RNZYS. Yachts have slipped moorings.. Stay off the water today! @MetService pic.twitter.com/lcKFvhSL7m
Pictures posted to social media show large waves crashing over the seawall onto the road and inundating parked cars.
Auckland Council spokesman Glyn Walters said the city's Civil Defence and Emergency Management bunker had been activated as the council dealt with reports of surface flooding, downed trees, power cuts and debris.
Mr Walters warned there would also be localised surface flooding "all over then place".
A trimaran smashes through the railings on Windsor Reserve on Devonport waterfront. Photo / Deanna Moran
At Devonport on the North Shore, a trimaran apparently broke free of its moorings and washed ashore. Photos show the yacht perched precariously on the footpath and foreshore of the beach.
Firefighters in the north of the country have been "flat tack" responding to wind damage this morning, with west Auckland and the North Shore apparently worst affected.
Northern fire communications operations manager Eric Smith said there had been a lot of calls to trees down on roads or power lines. There had also been calls to roofing tiles lifting.
Strongest winds & heavy rain across Northland/Auckland now moving South thru day http://t.co/nWZsJcyls1 ^DC pic.twitter.com/1vkiFZFUne
In Wellington, strong winds gusting to 120km/h, and possibly 140km/h in exposed places, were expected today.
The wild weather has already brought damage to the capital, with slips blocking a road in Karori and forcing the evacuation of two buildings in Oriental Bay.
Photo / Esther Kim
The first slip came down from the hillside behind an apartment building on Oriental Parade about 9.30pm yesterday. A water main also burst, and two buildings were evacuated.
A second slip blocked Nottingham St shortly before 6am today.
Further south, heavy rain was expected from about midday.
Flooding on Tamaki Drive. Photo / Nick Whiteacre
Surge in insurance calls
AA Insurance has fielded three times as many calls as normal as ex-tropical cyclone Ita continues to harass the country.
The company had received about 80 weather-related claims by 3pm today, a spokeswoman said.
About 80 per cent of those calls had come from the Auckland area, she said.
AA Insurance head of product Simon Hobbs said the most common types of damage had been wind related.
"We've had tree branches coming down on homes and cars, as well as fences and garden furniture being thrown around.
"If you need emergency repairs in order to keep your home watertight and warm please ring us as soon as you can. While there's no deadline to make a claim, the sooner you let us know, the sooner we can help you,'' he said.
Meanwhile, those expecting the cyclone further down the country should make preparations for their home.
"Now's a good time to check your property and secure anything that could cause damage to any part of your, or your neighbours' property,'' Mr Hobbs said.
"During a storm we generally have a number of preventable claims related to trampolines and other outdoor equipment flying over to the neighbours' and damaging their property, or creating havoc on our customers' properties.
"To avoid these types of incidents be sure to store away or secure items that may move during a storm, such as garden equipment, outdoor furniture and sports gear such as trampolines.''
Photo / Nicola Giles
By 4pm today, the fire service had responded to 1071 emergency calls around the country related to weather.
By the numbers:
* Northland: 37
* Auckland: 291
* Bay of Plenty: 76
* Waikato: 65
* Canterbury: 2
* Nelson: 50
* Otago: 1
* Western (North Island): 91
* West Coast (South Island): 227
* Wellington: 4