A short but furious burst of wild weather has left a trail of destruction across Northland, Coromandel and the Bay of Plenty.

Tropical cyclone Wilma hit overnight on Friday, causing evacuations, road closures, and damage to water and sewage treatment stations.

It was the second weekend in a row of high winds and torrential rain with Waiheke Island, in the Hauraki Gulf, one of the worst-hit areas.

Two Auckland women staying at Rocky Bay had one of the luckiest escapes when their bach plunged down a cliff.

The 80-year-old house is now a pile of splintered timber on the beach, but the two occupants were able to get out because their dog Roxy woke and wanted to get out.

Shirley Harris told 3News that when she went outside she saw the planks in the retaining wall coming away from the bank and hitting the house. She immediately woke the other person and they got out of the house.

"When we were halfway up the track we heard an almighty creak and groan and crash, so I don't know whether that was the water tank falling down or what."

Rocky Bay resident Coralie Edwards said the women escaped with nothing.

"They only had one carrier bag with them which got abandoned because the track was like a river. They were absolutely drenched and frozen, and quite shaken.

"But they got out safely with their two dogs."

North of Whangarei, another dog was not so lucky.

Truck driver Ron Leathley saw a vehicle lose control and slide into the Wairua River.

"One guy in a Land Cruiser ended up going off the edge and into the water," Leathley said. "He got out but his dog drowned... poor little dog."

A truck driver for almost 30 years, Leathley said he had never witnessed flooding like that suffered in the Far North over the past 36 hours.

About 70 people from Northland towns between Kaeo and Kawakawa sought emergency shelter due to rising floodwaters.

SH1 north of Auckland was closed, a low-lying section of SH11 between Kawakawa and Paihia in the Bay of Islands was closed by floodwaters, and SH2 between Tauranga and Whakatane was also impassable. The access road to Tawharanui Beach near Matakana was also cut off.

Roads on the Coromandel Peninsula were also affected, with numerous slips blocking access and boulders as big as cars being swept along with the debris.

In Tauranga, nine patients at Waipuna Hospice were evacuated as the Wairoa River flooded its car park. Yesterday morning the city recorded 50mm of rain in one hour.

Heavy rain also forced raw sewage to flow over properties and into the Whangamata harbour after the treatment station at Awarua Point stopped working. People were advised to keep out of the water.

In Tauranga, authorities had similar warnings for the city's harbour, where there were elevated bacteria levels caused by stormwater runoff, as well as multiple sewer overflows.

In parts of Northland, 280mm of rain fell in about 14 hours from 1pm on Friday. Leigh, just north of Auckland, received 193mm.

Wilma is now well clear of New Zealand and moving fast across the Pacific Ocean.

But she has left strong winds in her wake.

In the Colville Channel between Coromandel and Great Barrier Island the wind was recorded at 124km/h yesterday.

Gale-force gusts were expected in exposed areas across the North Island overnight and in exposed parts of Canterbury, the West Coast and Southland.

The system killed three people in Samoa and caused major damage to homes and farms in Tonga.

- © Fairfax NZ News