Residents evacuated in Marlborough yesterday because of the flooded Wairau River have been told they can return to their homes.
Evacuated residents from Tuamarina, Spring Creek and the Lower Wairau can return to their homes from midday.
However, some from other areas will have to wait until two helicopters have assessed the condition of the roads and rivers.
Evacuees can now pick up their vehicles stranded along SH1 between Picton and Blenheim. Stranded vehicles will also be removed by police if the owner cannot be located or the vehicle is damaged.
State Highway 1 including the Wairau River bridge was expected to re-open from midday.
SH6 between Renwick and Havelock is not expected to open until mid-afternoon at the earliest.
SH63 is not expected to re-open for some days. Many local roads are still closed.
More than 900 people from 500 properties in Marlborough were warned yesterday to leave their homes as the region was hit by its largest flood on record.
The Wairau River overflowed its banks at Tuamarina, Renwick and Spring Creek.
Marlborough District Council deputy mayor Nadine Taylor earlier said the river stopbank was being inspected to make sure conditions were safe.
"The river has gone down but it's still raging and we want to make sure that stopbank, that we've full confidence in it before we let those other residents go back in," she said.
Taylor urged people to keep in touch with authorities as they start to return home.
Incident controller Richard Coningham had said the district council's engineers would use helicopters this morning to assess the damage along rivers and on roads.
MetService forecaster Andy Best said more rain, possibly heavy, was expected in Marlborough from this afternoon but conditions were expected to ease from tomorrow.
Tasman District Council said while some rain is forecast this afternoon, it is not expected to cause any concern.
State Highway 6 across the Tākaka Hill reopened this morning. However, SH6 into Nelson from Blenheim is still closed between Renwick and Rai Valley.
Further south, State Highway 6 from Kawatiri Junction to Murchison and State Highway 65 through Shenandoah are closed due to multiple slips.
The Transport Agency says contractors expect to open a route through to Nelson via state highways six and 65 by the end of the day.
Yesterday, parts of the West Coast and top of the South Island had been cut off due to flooding, while states of emergency were declared in Buller, as well as Marlborough.
Close to 1000 people spent the night in evacuation centres in the Buller district, and at least 100 homes have been flooded.
An extra 10 Defence Force personnel from Burnham Military Camp have been sent to remote stranded areas this morning.
Fourteen defence personnel are already helping with emergency coordination and relief work.
A Defence Force helicopter is taking to the air this afternoon to check on people living in hard-to-reach areas of Buller.
Flood recovery efforts in Westport are in full swing, as river levels recede.
Soldiers are helping local emergency staff to identify and cordon off flood-damaged parts of the town as hundreds of evacuees wait to hear when they can return home.
However, authorities say there are still risks from contaminated floodwater and electrical hazards.
Buller mayor Jamie Cleine said extensive damage was likely to be revealed throughout the district.
Half of Westport's residents had been told to evacuate their homes because of the threat from overflowing rivers.
Cleine said some residents face a long road to recovery in the flood-struck region.
More than 2000 residents are unable to return to their sodden homes in the district, where contaminated floodwaters pose a health risk.
Cleine said it will be a huge event for some residents to overcome.
He expects many locals will spend another night in the evacuation centre, as people are still being urged to stay put.
Waka Kotahi NZ Transport Agency journey manager Tresca Forrester said crews had been out since first light assessing road damage, inspecting bridges and clearing debris from blocked and flooded highways.
Access to some cut-off communities, like those in Westport, through to Golden Bay, had been re-established, with the SH67 Buller Bridge, SH60 from Collingwood to Riwaka and SH6 from Hira to Rai Valley all re-opened, she said.