Many roads around the West Coast are affected by slips and debris, according to the Transport Agency, Waka Kotahi.
Waka Kotahi senior network manager Colin Hey said road crews had cleared many of the slips, but there were still slips and debris along State Highway 6 heading into Westport, around the Fox Hills, and elsewhere on the West Coast.
"We will have a better picture later today of road conditions, given the work underway and the rain which is still coming through," Hey said.
He said essential clearance work and patrolling would continue over the weekend but major road reinstatement would not start until after the long weekend.
SH67 north of Westport to Mokihinui was cleared earlier today and is now open to a single lane.
Greymouth south to Franz Josef is largely clear, except for some surface flooding.
"We are still assessing one area between Bruce Bay and Fox township and will have more to report on that later (Friday). More clearance work is underway between Bruce Bay and Haast," Hey said.
SH6 between Hira and Rai Valley, Ngā Whangamoa, is closed due to slash and slip material on the road and is likely to remain closed overnight.
An alternative route between Blenheim and Nelson is available via SH63.
People are encouraged to avoid the Marlborough Sounds local roads if possible over the long weekend.
Waka Kotahi Top of the South system manager Andrew James said the roads were still in a fragile state from the last storm and there was potential for further disruption.
Kenepuru Road remains closed from that earlier storm.
Meanwhile, a partial evacuation of Westport has been ordered in areas believed to be at a direct threat of flooding later tonight or in the early hours of Saturday morning.
Buller District Mayor Jamie Cleine told Midday Report a technical team would reassess the evacuation areas this afternoon to ensure they were adequate.
There was no access via road to smaller districts in northern areas, like Mokihinui and Karamea, but they had good Civil Defence plans for potential evacuations, Cleine said.
"The airforce and civilian helicopters are now available in town here to be dispatched out there if there is any need for resources to be deployed out that way as well."