The Wellington coastal community of Makara will remain cut off overnight after flooding on both access roads.
The community west of the city was isolated after steady rain, which caused slips and flooding today in central New Zealand.
A Wellington City Council spokesman said sections of Makara Beach Rd and the Takarau Gorge Rd, between Makara and Johnsonville, were flooded.
The roads will remain closed until 7am tomorrow, when engineers would assess whether the flooding had caused any damage.
The heavy rain also closed the South Island's main road after a slip on State Highway 1 south of Blenheim.
Both lanes were blocked about 20km south of Ward, sending motorists on a long detour via Lewis Pass.
New Zealand Transport Authority spokesman Anthony Frith said State Highway 1 had since reopened.
"We're dealing with a number of localised slips, but not anticipating any major traffic delays,'' he said.
"Crews are out scouring the network, removing hazards. We ask motorists to take care and drive to conditions.''
A police southern communications spokesman said emergency services were earlier called to a number of flooding incidents around Queenstown.
The rain also caused surface flooding around the lower North Island.