State Highway 1 has reopened between Blenheim and Ward on Wednesday morning, but SH7 Lewis Pass remains closed.
Both routes between Nelson and Christchurch were closed on Tuesday due to flooding, crashes, and fires.
SH1 remained closed overnight, but reopened around 8.30am.
SH7 remains closed between Hanmer Springs turnoff and Springs Junction, with images showing a section of the road washed out near the Engineers Camp.
An NZTA spokesperson says, with the Boyle River running high at the site of the erosion, and more rain predicted through this week, further erosion is possible.
The roading teams will be monitoring the situation and will be seeking to fill the eroded areas when conditions allow.
State Highway 65 has reopened to traffic on Wednesday morning following bad weather and flooding in the area on Tuesday.
On State Highway 6, at Dellows Bluff near Murchison, the highway is down to one lane due to a slip – delays can be expected in this area.
While the weather has improved, road users are asked to drive with care on South Island highways as work continues to repair damage caused by yesterday’s bad weather
