Heavy rain hits Dunedin, surface flooding across city

Heavy rainfall has arrived in Dunedin earlier than expected and is forecast to continue overnight, with surface flooding and some land instability reported.

Dunedin's Civil Defence bunker has been activated, with a rare red-level warning issued for coastal Dunedin and Clutha for heavy rain that could cause significant flooding and slips.

State highways have also closed in Otago, because of snow.

On Sunday evening MetService updated its forecast with a further 50 to 70 mm of rain expected on top of what has already fallen, especially from Milton northwards between 8pm Sunday and 10am Monday.

"Intensities are now generally decreasing, but some locations may still experience 10 to 15 mm/h until early Monday morning. Snow is likely above 300 metres."

The forecaster this was a significant amount of rain for low lying areas, especially around low lying parts of Dunedin and the Taieri Plain.

There was a high chance the orange heavy rain warning for coastal parts of north Otago would also be upgraded to a red warning.

Civil Defence controller Sandy Graham said the heavy rainfall forecast for this evening arrived earlier than expected.

"We also know the situation can change quickly, so the Civil Defence bunker will continue to operate overnight, and we'll have a team of staff and contractors responding to issues as they emerge.

"We're actively monitoring inland areas and rivers too - alongside our colleagues at the Otago Regional Council and MetService - and we'll continue to work closely and collaboratively."

Civil Defence said was there was a lot of surface flooding from Milton in the south to Waikouaiti in the north along coastal Otago, "but no major issues at this stage".

Dunedin Mayor Sophie Barker said they had prepared for the worst.

"We've had our contractors out doing a whole lot of work to make sure that we've checked and cleared the stormwater systems," she said.

"We are all keeping a really, really close eye on the level of rain and how our pumps and our pipes are handling those."

She said flood protection barriers were out on Surrey Street and there were sandbagging stations in three different areas.

"We are ready and prepared if we needed to evacuate anyone as well."

She said South Dunedin had been the hardest hit, although areas like Middlemarch were also a concern.

While the rain was now predicted to ease off, she said weather could be fluid so it was still a case of "wait and see".

Earlier, Barker said it was a "significant weather event" across the city.

"We're now seeing localised incidents of surface flooding and minor land instability.

"As a result, we're asking people to stay home if possible, avoid any unnecessary travel and keep up to date with all the latest information.

"Our roading and pipe networks are coping well so far, but there's more rain to come tonight. If anyone feels unsafe, they should self-evacuate to friends or family if possible in the first instance.

"Anyone in danger should call 111 and seek help from emergency services, and anyone with nowhere else to go can contact the DCC for support on 03 477 4000."

Mosgiel wasterwater failure

Mosgiel residents are being asked not to shower or flush their toilets for the next few hours while a malfunctioning valve at the wastewater pumping system is repaired.

The issue was reported to the Dunedin City Council Emergency Operations Centre just after 7pm, as heavy rain puts the network under strain.

Graham said the teams will work as quickly as possible to resolve the issue.

"Heavy rain means that there is some storm water in the waste water system, which means that we've got increased volume," Graham said.

"The system is full - without being able to open this valve, we can't empty it."

"It would be great if Mosgiel residents, for the next few hours, didn't flush their toilets or use their showers or baths, or put anything down the drain if they can avoid it. That will give the team a chance to get in, and fix this malfunctioning valve."

MetService meteorologist John Law said the low-pressure system would be slow to clear.

"The rainfall tonight in that coastal fringe of Dunedin down towards Clutha could be as much as 80-120mm of rain," he said. "On average, in places like Dunedin city, we're looking at about 75mm of rainfall, normally what we'd find throughout the entirety of July.

"It's a substantial amount of rainfall, a significant amount, especially for the eastern side of the country."

State highways have also closed because of snow in the South Island.

State Highway 8 is closed through the Lindis Pass, from Omarama to Tarras and from Fairlie to Lake Pukaki.

State Highway 85 is closed from Palmerston to Kyeburn and State Highway 87 from Kyeburn to Outram.

Part of State Highway 88, from Sawyers Bay to Port Chalmers, is closed, because of flooding, but a detour is in place.

MetService has also issued road snowfall warnings for the Haast and Lindis Passes, Crown Range Road and State Highway 1, between Dunedin and Waitati.

Weather warnings

Coastal Dunedin and Clutha are under a red heavy rain warning until 9am Monday.

A heavy snow warning is in place for Otago, excluding coastal areas, and northern Southland (north of about Lumsden) until 6am Monday.

A heavy rain warning is in place for coastal parts of north Otago until 9am Monday.

At 4pm Monday, a heavy rain warning kicks in for Marlborough and inland Canterbury, north of Lake Sumner, excluding Marlborough Sounds.

RNZ is New Zealand's statutory civil defence lifeline radio broadcaster, providing vital information and updates as they come to hand. All frequencies can be found here.

'Conditions will isolate communities'

MetService's red rain warning for coastal Dunedin and Clutha covered a period of 21 hours from 12pm Sunday until 9am Monday.

"Threat to life from dangerous river conditions, significant flooding and slips," the warning said. "Conditions will disrupt travel, make some roads impassable and isolate communities.

"Do not enter floodwaters and avoid travel. Act quickly to self-evacuate, if you see rising water.

"Be ready for power and communications outages."

An orange heavy rain warning was also in place from 12pm Sunday until 9am Monday for coastal parts of north Otago, with a high chance of an upgrade to a red warning.

MetService issued a heavy snow warning for Otago, excluding coastal areas, and northern Southland (north of about Lumsden) from 9am Sunday until 6am Monday.

Dunedin City Council said sandbags were available at the Dunedin Ice Stadium car park in St Kilda and the Mosgiel Memorial Park gym car park in Mosgiel.

Flood protection barriers were being installed in Surrey Street on Sunday afternoon.

The council said the rain was already causing localised flooding on roads around the city and there was a risk of slips in some places, as the weather deteriorated.

"We are working hard to ensure the city is ready and all steps are taken to minimise any impacts, and our contractors and staff are on standby to respond to any incidents," the council said.

The NZ Transport Agency was also warning of road closures in Otago and Southland, with road snowfall warnings for the Haast Pass (SH6), Lindis Pass (SH8), Crown Range Road and Dunedin to Waitati Highway (SH1).

'It gives you a bit of anxiety'

South Dunedin's Daniel Suddaby said his garage flooded last time the city was under a red rain warning.

"It gives you a bit of anxiety," he said. "It always seems to rain the heaviest in the middle of the night. which is niggly.

"My home is safe, it's never flooded inside, just a little bit of water underneath. For collecting 20 sandbags, it's worth doing."

Another South Dunedin homeowner, who did not want to be named, told RNZ his house had not previously flooded, but he was sandbagging as a precaution.

"I was here in the 2015 flood and the 2024 [flood]," he said. "Clearly, we've got a major problem with our drainage issues out here.

"Hopefully we're going to get the council onto that and get some upgrading of our infrastructure. At the moment, really all we can do is just look after ourselves and make sure that our sections and properties are okay.

"Forearmed is forewarned."

Clutha District Council said local Civil Defence would continue to monitor the situation with Otago Civil Defence Emergency Management and Otago Regional Council.

"We expect there will be surface flooding in low-lying areas," the council said. "Please avoid travel if possible and drive to conditions."

Further north, MetService had issued an orange heavy rain warning for Marlborough and inland Canterbury, north of Lake Sumner, excluding the Marlborough Sounds, from 4pm Monday until 6pm Tuesday.

Forecasters expected 150-200mm of rain about the ranges and 60-90mm nearer the coast.

The red weather warning was the sixth that MetService had issued this year.

MetService said the escalation to a red warning came as onshore winds brought a steady feed of rainfall into eastern parts of the South Island through Sunday and into Monday.

MetService meteorologist John Law said there was a mix of heavy rain and strong winds heading into Sunday and Monday, as an area of low pressure slowly moved across the country.

"The areas of greatest concern are in the east of the South Island, with rain pushing into Dunedin and Otago today (Sunday), before heading northwards into Canterbury and Marlborough during Monday."

Rest of the South Island

Another orange heavy rain warning, from 4pm Monday until 6pm Tuesday, has been issued for Marlborough and inland Canterbury north of Lake Sumner, excluding Marlborough Sounds.

MetService expected 50-200mm of rain about the ranges, and 60 to 90 mm nearer the coast with a moderate chance of turning into a red warning.

A heavy rain watch was in place for Mainland Southland (not including northern Southland above 400 metres) until 11pm Sunday.

Inland Canterbury about and north of the Rangitata River (excluding areas covered by warning) was also in for a heavy rain watch from 12pm Monday.

Fiordland north of Doubtful Sound and west of the main divide is also under a strong wind watch until 6pm Monday.

The West Coast south of Westport will go under a strong wind watch from 10am Monday.

An orange heavy snow warning is in place for northern Southland and Otago, excluding coastal areas, and a heavy snow watch will be in place for South Canterbury south of the Rangitata River from 3am Monday till 3am Tuesday.

MetService meteorologist Maddy Neal said the region could be in for some heavy accumulations of snow at some levels.

With the warning in northern Southland and parts of Otago going into effect from 6am Sunday until 6am Monday, Neal said there were no current "observations" of snowfall.

"As we progress through the day, the snow level is going to lower, which is why we have a warning out, because people in some urban areas, including parts of Central Otago, Northern Southland and even potentially urban areas of Dunedin, may see some snow later in the day, as that snow level lowers down to possibly 200 metres in places."

She said the chance of the orange warning being upgraded to a red warning was now moderate.

"It's not a red warning, but we could expect potentially some changes, as we go through the day [on Sunday]."

Neal also added there was a chance that snow accumulation could reach one metre in areas above 800m.

A warning for Milford Road was lifted at 9am Sunday, with warnings for Lindis Pass and Crown Range Road to go until Sunday night. Haast Pass and Dunedin to Waitati Highway will have a warning until Monday morning.

Neal said they had expected rain to turn to snow near the summit of Milford Road on Saturday night and Sunday morning, with a forecast of 2-5cm of snow and lesser amounts down to 800 metres.

For other roads under warnings, snow was expected to accumulate throughout the day and night, and Neal urged drivers to be cautious, especially with the start of the school holidays.

"We just want to make sure that people are driving to the conditions and thinking about changing their travel plans, if they're going to be experiencing disruptions from snow."