Whangarei District Council is warning that slip-damaged roads could become perilous in the next few days, with more rain forecast.
Contractors are working to clear hundreds of slips around Northland after Cyclone Wilma dumped two months' worth of rain on the region in one night two weeks ago.
Many roads are down to one lane and a few remain closed.
The District Council says slippery yellow clay is still falling from hillsides and car tyres are tracking it along the roads.
It says rain forecast for Friday and the weekend will turn those roads into a skating rink and motorists should take extreme care.