Heavy persistent rain is expected to batter parts of the northern NSW coastline with some regions being warned to expect up to 200mm of rain and flash flooding over the long weekend.
Areas from Port Macquarie up to Lismore can expect a soggy long weekend and residents in low-lying areas need to be prepared, the State Emergency Service says.
"There's heavy rain for the next two or three days and it's starting to impact with lower level flooding. So it is a watch and prepare situation," an SES spokeswoman told AAP on Sunday.
Residents in low-lying areas are being urged to move stock and pumps and prepare for isolation, she said.
There are flood watches on seven or eight rivers in the Mid North Coast up to the Northern Rivers, she said.
Lismore, Grafton, Coffs Harbour, Port Macquarie, Sawtell and Dorrigo may be affected, according to the weather bureau.
Lismore, which was badly hit by floods at the end of March after Queensland's cyclone Debbie brought unprecedented rainfalls to northern NSW, has had more than 100mm of rain in the past 24 hours.
Evans Head and Yamba have already copped more than 130mm or rain in the past 24 hours.
SES is warning drivers to be mindful of the poor conditions this long weekend.
A severe weather warning for the Hunter region has been cancelled.
