More wild weather is on the way - with heavy rain and snow expected for parts of the South Island and the cancellation of Cook Strait ferries.
Snowfall warnings have been issued for Canterbury alpine roads the Lewis Pass (State Highway 7), Arthur's Pass and Porters Pass (both SH73), and the Lindis Pass (SH8) in Otago. Porters Pass was forecast to get between 10 and 15cm.
The Waitaki District Council advised on social media this afternoon that a heavy snow warning has been issued for the upper part of the district.
Between 12cm and 20cm of snow was forecast to settle to about 800 metres, with lesser amounts down to 700m in the Canterbury High Country, south of the Rangitata River, from 9pm today until 9am tomorrow.
"This may cause disruption to travel, while damage to trees and powerlines were possible. Cold conditions may cause stress for livestock."
The council advised people to prepare for snow, cold temperatures and possible power outages.
"If you must travel, drive cautiously, and ensure you have snow chains, sleeping bags, warm clothing and emergency items."
Meanwhile, orange heavy rain warnings were in place for Kaikoura, Banks Peninsula and Canterbury, while a heavy rain watch is in place for Canterbury south of Amberley, and north of Timaru.
MetService said there was a high chance of an upgrade to a red heavy rain warning in Canterbury, north of Amberley, covering the period from 10am today until 9am tomorrow.
The forecast was for 160mm to 210mm of rain, on top of what has already accumulated, with snow gradually lowering to 700 metres tonight.
That meant dangerous river conditions, flooding and slips were likely. Dangerous driving conditions and road closures were also expected.
An orange warning also covered the Kaikoura Coast and ranges, expected to get 150mm to 200mm of rain from midday today until 6am on Friday.
In the North Island, heavy swell warnings are in effect for the Wellington and Wairarapa coasts.
Conditions should start clearing up by the weekend, MetService meteorologist Mmathapelo Makgabutlane said.
"It is expected to be at least a couple of days. And so today, Wednesday, we're expecting everything to really start kicking off. Tomorrow, Thursday, will be another day to keep a close eye on, as well as Friday.
"But it does look like as we head into the weekend, most of the country should be rid of that weather and by Sunday, things are looking pretty good across the country."
Snow on alpine roads
Lewis Pass (SH7)
Valid: 15 hours from 9am on Thursday until 12am on Friday
Snow expected to affect the road near the summit, where 2 to 5cm is likely to accumulate.
Arthurs Pass (SH73)
Valid: 21 hours from 9pm on Wednesday to 6pm on Thursday
Snow forecast to affect the road near the summit, where 1 to 3cm of snow may settle at times. Lesser amounts likely lower down.
Porters Pass (SH73)
Valid: 18 hours from 9pm on Wednesday until 3pm on Thursday
Between 10 to 15 cm of snow expected to settle on the road near the summit, with lesser amounts to 700 metres.
Lindis Pass (SH8)
Valid: 12 hours from 8pm on Wednesday until 8am on Thursday
Snow set to affect the road near the summit, where 1 to 3cm is likely to settle. Lesser amounts likely lower down.
Makgabutlane said the would be welcome news for ski fields.
"At this early stage, I'm sure we'll definitely take any snow that we can get. However, it is quite unseasonal, so in terms of the ski fields, we'll definitely be crossing our fingers for more snowfall as the season goes on."
Christchurch roads closed
Christchurch City Council contractors have been preparing ahead of the downpour, clearing gutters, sumps, stormwater grates and beach outfalls.
New Brighton Rd between Rawson St and Pages Rd, and Avonside Dr between Wainoni Rd and Kerrs Rd, were closed due to flooding from late this morning.
The heaviest rainfall was expected in the western Port Hills and the southern part of Banks Peninsula, the council said.
"It's a good idea to clear your rain guttering and drains and if you know there are leaves blocking sumps or drains by your property, it would help us if you could remove them, and put them in your green wheelie bin.
"Our stormwater network is designed to cope with heavy rain and our road network is also part of our stormwater network playing an important role during wet weather events. In most parts of the city our roads have been designed as secondary flow paths for stormwater so in heavy rain its normal to see some flooding on our roads."
The council was also managing water levels in the Ōpāwaho Heathcote River.
"Residents along the upper and mid-reaches of the river can expect fluctuations of water levels at any time before, during and after the rainfall event, even during periods of dry weather. This is to reduce peak flood levels during the rainfall event by maximising the use of the storage volume in the basins."
Time to hunker down: Hurunui mayor
Hurunui District mayor Marie Black said rain had been falling steadily in the region today.
"It is very much a watch and wait situation. The prediction is for heavier falls - but from a district perspective, there are no issues that we can't manage at this point, and we've got our teams ready to go to support the community as if and when that's required."
The worst of the rain was expected north of Amberley, which encompassed most of the district and she said preparation was under way should the warning be upgraded to red.
"If it does eventuate, we've had good warning by the MetService and obviously we will manage that accordingly."
Black said people should take care on the roads and take the chance to check in on friends and neighbours. "This is really the time when we need to hunker down and look after each other."
Canterbury Civil Defence and Emergency Management group controller James Thompson this afternoon said surface flooding was expected in the Hurunui, Waimakariri and Selwyn districts, with swollen smaller rivers.
"We're looking at rainfall that is the equivalent of two to three times what we'd normally see in a month. It is significant rain," he said.
However, Thompson said councils were not expecting big rivers to break their banks.
"At the moment, particularly from a flood control point of view, we're not seeing it being red at the moment, but we're monitoring and fully prepared in case we do need to make it red," he said.
Ferries cancelled
Strong wind watches have been issued for the Buller, Grey, Westland and Nelson Lakes districts, the Marlborough Sounds in the South Island and and Wellington, along the south coast, including Wairarapa north of Castlepoint, in the North Island.
Southeast winds may approach severe gale in exposed places.
MetService has issued heavy swell warnings for the 33-hour period between midday tomorrow and 9pm on Friday.
Waves of 6 metres were forecast off Wellington - Cape Terawhiti to Turakirae Head from 3pm tomorrow until noon on Friday, while swells rising to 7 metres were expected off Wairarapa - Turakirae Head from midday tomorrow until 9pm on Friday.
"This weather system that's bringing all of this weather that we're expecting is also going to be generating some large swells, but also the wind's generating some large waves on top of that and causing all sorts of problems and disruptions," Makgabutlane told RNZ's Morning Report programme today.
Interislander said it had cancelled crossings from 8.30pm today until 2.30am on Friday, and there would be extra sailings put on over the weekend to accommodate passengers. More cancellations were likely on Friday if conditions did not improve.
Bluebridge was cancelling sailings from 1.30pm today and all of tomorrow.
Wellington and coastal areas of the Wairarapa are bracing for severe gale southerly and southwesterly winds - gusting up to 130kmh - from Thursday morning through to midday Friday.
MetService meteorologist Lewis Ferris said the winds were expected to be the strongest southerlies to batter the capital in over a decade - since Wellington Airport measured southerlies of over 140kmh in 2013.
Homer Tunnel planned closures
The Homer Tunnel on the Milford Road (SH94) in Southland is closing from 6.30pm to 3am for maintenance works from today until May 2, then from May 3-23 from 6pm until 3am.
"No public access during these closures due to heavy equipment operating in tunnel."
- ODT Online and RNZ
