Crews are working to clear debris 3-4 metres deep after an overnight land slip on the West Coast.
State Highway 6 near Whataroa - north of Franz Josef Glacier - was closed around midnight after the 400 metre-long slip occured.
The area had 178mm of rainfall in a very localised spot over a short timespan.
Metservice meteorologist Robb Kerr says a severe weather watch was in place but the instantaneous and mobile nature of the front from the south-west didn't warrant a weather warning.
He says the area hasn't been as dry as the rest of the country and that this rainfall was the "straw that broke the camel's back."
NZTA Spokeswoman Moira Whinham says the road is not expected to open until Monday due to the depth of the material, with large trees, soil, rocks and streams cutting across the highway.
There is no local detour available, so drivers are advised to check the Transport Agency’s updates online.