About 1800 people are cut off from evacuation in NSW as rain continues to fall, the state’s SES says this morning.

A further 18,500 people have been told to prepare to evacuate, and 20,300 people are under evacuation orders.

Significant flooding is occurring on the Clarence River, with emergency warnings advising people to shelter in place for people living on Carrs Island, Grafton, and downstream on Harwood, Chatworth, Warregah and Goodwood Islands.

Residents on these islands will be isolated until flood waters recede.

Along the Richmond River, residents at Bungawalbin have been advised it is too late to leave the area and to seek refuge at higher ground due to major flooding. Major flooding is also occurring at Coraki.

Very heavy rain has fallen overnight in Queensland and in the Tweed Valley.

This rainfall has renewed flood levels across the region and is expected to last well across Monday in a number of places including Tumbulgum.

Residents were advised to evacuate Tumbulgum four days ago and should avoid returning until the flood waters recede.

Further south, the Macleay River may reach moderate flood levels at Kempsey and Smithtown, with residents advised to prepare to evacuate. Isolations are also possible at Hat Head, Crescent Head and South West Rocks due to flood waters across roads.

Meanwhile, a flood watch for minor flooding in the state’s north west and central west is in place.

Minor flooding is possible along the Upper Macintyre River, Gwydir River, Macintyre River, Peel River, Namoi River and Castlereagh River. The NSW SES has prepositioned flood rescue boats and rescue operators at high-risk locations.