Work is underway to clear debris, assess damage and re-open vital routes to reconnect severed South Island communities.
As the sun shines today after weekend floods devastated the region, Waka Kotahi is urging motorists to drive with care on some re-opened roads, with many having lane restrictions or lower speed limits.
Several state highways in the South Island remained closed after the weekend's flooding.
State Highway 65 from O'Sullivans Bridge to Springs Junction and SH6 between Murchison and Nelson was reopened this morning, following the reopening of SH6 between Nelson and Blenheim yesterday.
But SH6 Murchison to Inangahua remained closed and SH63 from Renwick to Tophouse was also closed.
It may take months to fully fix Queen Charlotte Drive, the scenic road between Picton and Havelock in the Marlborough Sounds.
Tasman and Marlborough were the most challenging areas of roading, the Transport Agency's journey manager Tresca Forrester told Morning Report.
Efforts to relink communities were ongoing and she expected work to go on for weeks.
Pot holes and wash-outs predominated on the West Coast roads, she said. But these were being probed for signs of more significant movement or damage. All bridges in the region had held up.
"In the West Coast we still have State Highway 6 through the upper and lower Buller Gorge shut and we are doing some inspections today to look at the damage," she said.
"There is damage, but it's not significant. However, it will still probably take weeks to repair."
Areas in the Marlborough and Tasman region, like the Waihopai Valley, were being inspected and work to open up the roads was ongoing.
"We are working really closely with with Civil Defence on those, so we are absolutely aware and everybody is working closely together to restore those things," she said.
Roads are not the only infrastructure disrupted. Boil-water notices remain for some West Coast communities due to the risk of contamination from the weekend's flooding.
Buller Emergency Management said residents of Westport, Carters Beach and surrounds should boil their water.
Water conservation notices apply to those catchments, as well as to Punakaiki and Inangahua Junction.
People are being told to minimise the use of toilets, showers, washing machines and dishwashers, which add load to sewerage systems.
Further north, in the Nelson-Marlborough area, boil-water notices are in place for Brightwater, Eighty Eight Valley, Tapawera and Wairau Valley.
MetService meteorologist Amy Rossiter said the wet weather would clear up today around Marlborough and Tasman.
Tomorrow would be sunny in the region, but more unsettled weather would follow on Wednesday, with heavy rain for the central North Island expected.
"Tomorrow we're looking at a fine day as narrow ridge moves over the country," she said.
"However we do have another system approaching late on Wednesday and that's going to bring some heavy rain again to western regions. But thankfully things will move quite quickly through Wednesday night into Thursday and so we shouldn't see a significant accumulation as we did with this system."
Heavy rain for North Island, including Taupō, Taranaki and possibly further north, was likely later in the week.
"There's potential for it to be heavy, but at this stage we haven't issued any Watchers warning. It's something to keep an eye on, definitely," she said.