Torrential rain, strong winds and big surf are pounding the coast, and flood warnings are in place for much of the coast.
The Bellinger, Orara, Nambucca, Macleay, Hastings and Manning rivers are all rising steadily, cutting off communities.
State Emergency Service crews are sandbagging to protect homes in the lower Clarence.
The Pacific Highway has been closed between Woolgoolga and Grafton, with more than half a metre of water across parts of the road.
Water is also across the highway north and south of Kempsey, at Clybucca, Bellimbopinni and the turn-off to Crescent Head.
A single lane has been kept open in those areas but congestion is expected to build through the morning.
The Waterfall Way between the Dorrigo plateau and the coast has also been cut by the rain.
The Roads and Traffic Authority has advised motorists travelling between Sydney and Brisbane to head inland and travel via the New England Highway.
