Helena Bay hill, north of Whangarei, opened again for two-way traffic on Monday afternoon after a big slip earlier in the day.
The local council says tonnes of debris have been cleared from Russell Road, but the surface is slippery with mud and motorists should drive with extreme care. A speed of no more than 30km/h is advised.
More slips are likely, with stormy weather forecast again for Tuesday.
The site is just south of the spot where a slip in 2007 closed the coastal road for several months.