Northland emergency services say motorists were caught in floodwaters that swamped much of the north on Friday night.
The worst-affected areas were from Kaeo to Kawakawa, where up to 260mm of rain fell in 12 hours.
The Kaitaia Fire Chief Colin Kitchen says one couple was lucky to survive when their car was swept off State Highway 1 near the Mangamuka Bridge late on Friday night.
"They got pushed right off the road.
"I think they actually ended up sitting on the roofs of their vehicles, so they were very lucky to get out of it really."
Mr Kitchen says three houses were evacuated in Kaitaia, but flood prevention work done on the Awanui River in recent years seems to have saved the town from worse damage.
About 70 people in the region who were evacuated to temporary welfare centres have now returned to their homes.
The electricity lines company Topenergy says 70 properties in Northland were still without power on Saturday evening after heavy rain caused damage to the network.
A spokeperson says power is out in Towai, Awarua and Kohumaru, and access for repair crews remains difficult due to flooding, slips and debris.
Vector says 113 properties are still without power in the Whangapiro area, near Wellsford.
Roads still closed
Roads around the upper North Island remain closed or damaged by slips and heavy rain.
Police say State Highway 1 north of Auckland has partially re-opened after extensive flooding.
One lane has been cleared at the Hoteo Bridge in Dome Valley near Warkworth.
The Transport Agency says flooding had been waist deep in places along the highway.
The alternative route, State Highway 16, is open in both directions.
In Northland the police say State Highway 11 between Kawakawa and Paihia and State Highway 1 between Kawakawa and Moerewa are both closed.
Police say State Highway 25 between Coromandel township and Whitianga is passable but requires extreme caution.
Cyclone on path to Chatham Islands
MetService says Cyclone Wilma dumped up to 260mm of rain in the Bay of Islands on Friday night.
Other areas to record more than 200mm in the past 24 hours include Kaikohe and Kerikeri, Whangarei Airport and Whitianga in Coromandel.
The cyclone is now heading towards the Chatham Islands, and is expected to bring heavy rain and high winds there until midnight on Saturday.
MetService says many areas are heading towards record-breaking rainfall levels for January.
River levels have begun to drop, but a number of roads and state highways from Kaitaia to Mangawhai remain closed by flooding, slips and fallen trees.
Some coastal communities in the Whangarei district are cut off by road and contractors are working to clear debris.
Police earlier said 10 homes near the Kaeo river were evacuated and residents were taken to the rugby club premises.
The Fire Service said two people were stuck up two trees at Pipiwai, northeast of Whangarei, for several hours.
A car went into a river in Wilson Road, Parakao. In Whakapara, three adults and a child roped themselves together before being rescued when their car became stuck in floodwaters.
Water supply no longer in danger
The Far North District Council says it has been able to repair a water treatment plant at Haruru Falls, easing fears that supplies would run out in some areas.
The council had earlier warned people in Paihia to save water after flooding damaged the treatment plant.
But the council now expects repairs to be completed on Saturday and storage reservoirs are expected to meet demand until then.
The council also issued a warning against taking shellfish or swimming in the Bay of Islands and Whangaroa Harbour.
It says there have been several raw sewage spills and there could be delays in getting new pumps from Auckland, because State Highway 1 is blocked.