Mangawhai spent the weekend cleaning up flooding damage from an enormous downpour on Friday night.

A regional council rain gauge recorded 250mm of rainfall in just three hours - on ground that was already saturated from Cyclone Gabrielle.

Cars were submerged and stuck, others temporarily stranded between slips, and some homes were flooded and their occupants evacuated.

The bill for roading repairs from Cyclone Gabrielle was already estimated at $120m in Northland alone, before Friday's storm.

Damien Hochberg had lived in his new house by the estuary for six months.

It is insured, but he estimates there is close to $500,000 worth of damage to his property and possessions, submerged in a metre of water on Friday.

Walls are soaked through, electrics ruined, furniture and appliances are unsalvagable, and he knows it will be months before he will live there again.

"The beds are buggered, there's no bed for me to sleep on, I've got no power, no nothing. So basically I just take out what's salvageable and just air the house out for the next couple of days."

Damien Hochberg's back yard and pool post-flood. Photo: RNZ / Samantha Olley

He said tradespeople will "have to take off all the walls - so every single wall will have the Gib taken off to assess how bad it is".

"It depends on how bad the wiring is if things have to be rewired, so it will be a long, long process".

On Friday night, the mangroves over the fence were rapidly submerged.

The water level on Damien Hochberg's fence. Photo: RNZ / Samantha Olley

"I jumped on the tanks and looked over. And next door was a stream, basically a river coming down with logs and all that floating through. So at that stage there, between that and our house fully flooding, it was probably the best part of 10 minutes."

He quickly put some valuables up high in his home, and evacuated in a dinghy.

"[We] took a boat, along the road, to get down the far end, because the was up to ... my chest."

A few houses down, Aidan Hand's place was just spared - the water reached a centimetre below the top of his deck.

He also hurriedly evacuated for the night - the only escape was climbing a back fence with his child.

Upon returning home on Saturday - there was a footbridge outside - the flood waters had carried down the street and dumped.

"It literally flowed from half a kilometre away and floated down in front of our house. Crazy."

Jenny Bateman lives in a house raised on piles, closer to the beach.

It was an island surrounded by flood water over the weekend, with no garden in sight.

"Just water, and just the one tree basically and that's it. That's normally just all lawn ... It is [the water is] up to my knees," she said on Saturday.

"When I'm walking along to the front door, up to the stairs, it's to my knees."

The view from the Campbell Park Christian Camp on Saturday. Photo: RNZ / Samantha Olley

Some evacuees went to family and friends' homes. Others - as well as travellers who were stranded by roads cut off - stayed at the Campbell Park Christian Camp.

There were 55 people in total there on Friday night and all had departed by lunchtime on Saturday.

Community members rushed to bring blankets, pillows and towels so the evacuees could make beds for the night.

Camp manager Julie Scott said: "There were people here who were flooded in their own properties and they're pumping out water today [Saturday] from their places but they still dropped off supplies to help other people."

Bedding and towels donated for evacuees on Friday night to the Campbell Park Christian Camp where 55 people stayed. Photo: RNZ / Samantha Olley

Roading workers and engineers have spent the weekend working to reopen key routes out of Mangawhai.

The Kaipara District Council expects Kaiwaka-Mangawhai Road may reopen midweek - and the road north to Waipū is expected to reopen tonight.

Traffic heading north is being diverted via Paparoa in the meantime - and trucks have to go even further through Dargaville.

On Friday night nearly every route in and out of Mangawhai was closed.

Harry Smithson's 15-minute drive south from Waipū became a 5.5 hour zig-zag of impassable road after impassable road.

"We weren't sure that we'd even get home," he told RNZ.

"We were like 'oh well, we will just see how close we can get and try to walk'. We were clueless.

"My family was ringing up and my phone was dead. So we had to try navigate all these back roads at night while it was pissing down."

Another resident, Sophia Smith, also tried to drive back from work to Kaiwaka on Friday and said: "It was torrential rain and I couldn't see more than a couple meters ahead of my windscreen."

She stayed in Mangawhai instead with her father.

"We watched over Mangawhai Central where we could see police cars and fire engines with their flashing lights on most of the evening.

"We watched over King Rd as the flooding got worse and worse. We saw a few cars driving through the floods with water up to their car windows."