Long recovery expected after Nelson-Tasman flooding - PM

It is clear an increase in funding will be needed to deal with the "devastating" impacts of the flooding across the top of the South Island, according to Prime Minister Jacinda Ardern.

"This is going to be a long recovery," Ardern said from Nelson on Monday morning.

Ardern said there was work going on in preparation for more adverse weather on the way.

She said it was likely it would not be as severe as last week's weather, however "because of the sheer amount of water that has fallen in this region, the slips are a concern".

Emergency Management Minister Kieran McAnulty is travelling to Marlborough to assess the damage there.

Ardern said they will work with local government in the recovery, with a focus on the roading network.

"There are isolated communities we need to get back up and connected," she said. "Some will have ongoing issues with potential slips."

The full cost will come over time, she said.