The Bureau of Meteorology has issued a severe weather warning for people on the North Coast and Mid North Coast and Northern Tablelands districts.
Rainfall is expected to intensify today, leading to the possibility of dangerous flash flooding.
Damaging winds are also forecast for the mid coast, averaging 60-70 kilometres an hour, and gusts exceeding 90 km/h.
At Coffs Harbour, waves are expected to exceed 5 metres in the surf zone which could affect Port Macquarie later in the day.
The combination of dangerous surf and unusually high tides could enhance the risk of significant beach erosion north from about Ballina.
The SES is urging people in affected areas to monitor the conditions closely, particularly in areas prone to flash flooding, stay indoors where possible, and never drive through floodwater.
