Severe weather to lash both islands, 'unusually strong' winds for Wgtn

Further severe weather is forecast to impact both islands tomorrow, bringing heavy rain, unusually strong winds for the capital and more disruption to transport.

A low-pressure system is deepening and moving across the country over the next 48 hours, sparking a large number of weather warnings.

MetService has issued orange heavy rain warnings for Bay of Plenty east of Ōpōtiki, Canterbury about and north of Amberley, Canterbury between Amberley and Timaru including Christchurch and Banks Peninsula, and the Kaikōura coast and ranges.

An orange strong wind warning is in place from tomorrow for both sides of Cook Strait, affecting Wellington, coastal areas of Wairarapa and coastal Marlborough south of Blenheim, including the Kaikōura coast.

Gusts of up to 130km/h could hit the capital and further disruption was expected to Cook Strait ferry services.

NZTA has warned motorists of possible lane closures on the Auckland Harbour Bridge tomorrow. SH1 would be blocked in Northland at the Mangamuka Gorge overnight into Thursday morning.

Orange heavy snow warnings were in force overnight for the Canterbury High Country, with 12 to 20cm of snow expected to fall above 800 metres.

Several watches were in place, including heavy rain watches for the eastern Bay of Plenty, Wairarapa and Wellington.

Strong wind watches were also forecast for Auckland, the Coromandel Peninsula, northern Waikato, inland Wairarapa, southern Hawke's Bay, Horowhenua and Kapiti Coast, the Marlborough Sounds, and the West Coast.

MetService's Heather Keats said the storm was "very widespread".

"It's covering almost the entire country," she said.

"Most of us will get at least a little taste of this system."

There was a "large amount of impactful rain" forecast for the east coast of the South Island, including a high chance of a red warning for Canterbury north and about Amberley which was "not to be ignored", Keats said.

Wellington was used to wind, but she said it was at "unusual levels even for them", with southerly gusts approaching 130km/h alongside high sustained wind speeds possible.

"When the wind is combined with the swell, and also the king tides that are expected, there will be elevated impacts from this weather, coastal inundation and erosion just to name a couple," Keats said.

She said it had been a "really wet and warm April", especially for the upper North Island.

"We did have a relatively quiet start to 2025, so it does feel like all the rough weather is now pushing over us but we are well into autumn now and we can expect the weather to become unstable at times."

Forecast swells of up to seven metres have forced a large number of cancellations on both the Interislander and Bluebridge over the coming days.

In the Far North, SH1 through the Mangamuka Gorge has been closed since yesterday due to a slip.

In an update at 5pm, NZTA said the road would remain closed overnight.

"Contractors will be on-site with specialist machinery tomorrow morning to remove loose material above the slip site in a safe and controlled manner," a spokesperson said.

Earlier, the agency said contractors were monitoring the movement of the hillside following recent heavy rain and another slip was expected.

"The geology and varying terrain through the Mangamuka Gorge mean it will always be susceptible to some movement during severe weather, like what we’ve seen over the past two to three weeks."

In Auckland, NZTA has warned drivers to prepare for the possibility of short-notice lane closures or reduced speeds on the Auckland Harbour Bridge, including at morning rush hour tomorrow.

"Wind gusts of 75-89 km/h are forecast for the bridge between 4am and 9am tomorrow, triggering an amber alert. Between 9am and midday, gusts may reach 90-95 km/h, potentially triggering a red alert," a spokesperson said.

"Wind gusts of 75-85km/h are forecast for between midday and 7pm, triggering another amber alert. The bridge will remain in a four-by-four configuration during peak traffic tomorrow. However, under an amber alert, speed limits may be reduced and some lanes on the bridge may close. Under a red alert, we may close all lanes on the bridge.

"When wind gusts reach 90km/h, we close all lanes because it’s unsafe for any vehicle to be on the bridge and the bridge structure is vulnerable to vehicle impacts."

Drivers of high-sided vehicles and motorcyclists were urged to travel around the harbour, as an alternative, using the Western Ring Route via State Highway 18.

Heavy rain warnings – orange

Bay of Plenty east of Ōpōtiki – 29 hours from 10am Wednesday to 3pm Thursday

Canterbury about and north of Amberley – 35 hours from 10am Wednesday to 9pm Thursday

Canterbury between Amberley and Timaru, including Christchurch and Banks Peninsula – 32 hours from 10am Wednesday to 6pm Thursday

Kaikōura coast and ranges – 44 hours from 10am Wednesday to 6am Friday

Strong wind warnings – orange

Wellington – 21 hours from 3am Thursday to midnight

Coastal areas of Wairarapa – 15 hours from 9am Thursday to midnight

Coastal Marlborough south of Blenheim, including the Kaikōura Coast – 21 hours from 1am Thursday to 10pm.

Heavy snow warnings – orange

Canterbury High Country south of the Rangitata River – 12 hours from 9pm Wednesday to 9am Thursday

Heavy rain watches

Bay of Plenty about and west of Ōpōtiki – 11 hours from 10am to 9pm Wednesday

Wairarapa – 8 hours from 1pm to 9pm Wednesday

Wellington – 45 hours from 6pm Wednesday to 3pm Friday

Strong wind watches

Auckland, Great Barrier Island, Coromandel Peninsula, and Waikato north of Hamilton – 5 hours from 7am Thursday to noon

Inland areas of Wairarapa, the Tararua District, and Hawke's Bay south of Hastings – 12 hours from 1pm Thursday to 1am Friday

Horowhenua and Kapiti Coast – 13 hours from 9am Thursday to 10pm

Marlborough Sounds – 18 hours from 6pm Wednesday to noon Thursday

Buller, Grey and Westland Districts, also the Nelson Lakes – 27 hours from noon Wednesday to 3pm Thursday