At least 15 homes are uninhabitable after flash flooding in Plimmerton, north of Wellington, which also briefly closed State Highway 1.
Torrential rain about 10am sent water rushing through peoples homes.
Plimmerton fire chief Carl Mills said there was nothing crews with pumps could do to hold back the water, which was made worse due to high tide happening at the same time.
"With the extra rain that came it really got too high, and went into where people's main living spaces are.
"In one place if you're in the driveway I think the water was a couple of metres deep, and probably another half a metre deep in the homes in some cases."
Firefighters visited about 65 properties in Plimmerton's Karehana Bay, which bore the brunt of the flooding, and Fire and Emergency NZ took 24 111 calls connected to the deluge.
Mills said the sun was now shining and making life easier for residents who were recovering any salvageable belongings and clearing silt and debris from inside houses and yards.
The Plimmerton fire station is open to any residents forced to flee their homes.
Roads and properties in nearby Titahi Bay have also flooded. The Titahi Bay Fire Brigade posted a warning online asking for people to take care of hidden dangers under the water.
"We've been out all morning in the wet assisting some families with flood damage and pumping water away from their homes.
"Please take care around flooded areas with contaminants, open hidden drains etc."
With more rain coming, they asked residents to check that drains around their home are not blocked, so water can drain.
A Dimock Street resident said she was sick of the repeated flooding problems in her street.
"There's flooded homes, heaps of mess on the street, rubbish and sludge to clean up now. My neighbours had cars lost in the floods over the years, including today ... it's half under the brown water.
"The flooding has been recurring in our street for years and it gets worse each time. Porirua homeowners pay amongst the highest rates in New Zealand and Porirua City Council do nothing to improve the situation. Rents in Porirua are the highest in New Zealand - so unfair!"
Mana Archery Club was holding a coaching course at their club in Plimmerton Domain this morning when the rain started, and many there found themselves trapped.
Club committee member Matt Kelland said when they started the course at 9am it was raining.
"I was just really surprised it all happened so quick. We came out at about 11am for break and pretty much the whole green and most of the area was under water, we didn't notice until we came out.
"By midday the bowling green started to fill up with water, and after 15 minutes it was completely full."
He said they became worried the club rooms would flood, so members quickly lifted everything they could off the floor.
The car park had flooded, which meant those in the domain couldn't get out.
"A couple of people got out in their 4WD got out earlier when it wasn't quite as high, but the rest of us can't get out because the cars are too low," Kelland said.
State Highway 1 has reopened after the rain in Porirua caused major traffic delays and road closures this morning.
The Plimmerton roundabout on State Highway One had closed due to flooding, and the road from there to Paekākāriki was also shut down.
But by 2pm the Transport Agency said both lanes have been reopened on the main highway. However, Grays Road and the Paekākāriki Hill Road remain closed.
Motorists are being asked to drive carefully and to follow directions given by emergency services, and traffic is heavily backed up backed up.
A Porirua engineer said the SH1 Plimmerton roundabout has had flooding problems for many years, but over recent years the rainfalls have been heavier and caused more problems.
Drainage works were needed to fix the issue, which would cause ongoing problems for SH1 otherwise, he said.
Until Transmission Gully opens, traffic between Wellington and Kāpiti faces detours of hours through the Wairarapa as an alternative route, if the highway roundabout at Plimmerton closes.
The Transport Agency was not able to answer questions about past flooding or plans for drainage work at the roundabout. Its Wellington Regional Transport Systems Manager Mark Owen said today's flooding was a unique weather event, and it works closely with local councils and Wellington Water to ensure drainage on the highways works effectively.
He said the agency "will work with our partners to assess whether there is anything we can do to minimise the impact of such events in the future."
FINAL UPDATE 2:55PM— Waka Kotahi NZTA Wellington (@WakaKotahiWgtn) November 29, 2020
Delays due to this flooding at Plimmerton have now CLEARED and the road is fully OPEN. Thank you for your patience today. ^EW https://t.co/96g50bVzuW
MetService says some areas in the region recorded between 20-30 millimetres of rain in a single hour as the front went through.
Forecaster David Miller said while the rain is easing, there could be more downpours over the next day or so.
Heavy rain and southerly gales are also expected for the Marlborough Sounds and the Tararua Range south of Levin.
The rain has finally cleared Wellington. Here is a time-lapse of the south coast from our friends at SnapitHD and Victoria University. In the 6hrs to 10am Kelburn recorded 22mm of rain, Otaki 36mm, Paraparaumu 41mm and Waikanae 58mm. ^AB pic.twitter.com/vqkI1MnLPm— MetService (@MetService) November 28, 2020
Meanwhile Wellington Water has had emergency service crews working in Plimmerton clearing culverts and flushing pipes, to ensure floodwaters can drain.
Staff from the service are working with Porirua City Council to find emergency accommodation for families affected by the flooding.