The Mid North Coast is on high alert with the Bureau of Meteorology issuing a severe weather warning.
Up to 200 millimetres of rain is set to fall in the next 24 hours between Coffs Harbour and Port Stephens.
Some catchments are set to flood by late Wednesday. Flash flooding is also possible.
“Being school holidays people are travelling and camping in the area and we need people to be mindful of the weather conditions road closures and flood safety,” Tony McMullen, from the State Emergency Service, said.
The heavy rain is set to ease by Thursday.