Already flooded parts of NSW face the prospect of further heavy rain that could cause more inundation as the cleanup continues around the state.
NSW Deputy Premier Paul Toole says help from the defence force for recovery efforts was needed "right now".
The Bureau of Meteorology has issued multiple flood warnings on Sunday, with heavy rain and river rises expected to continue into Monday in areas already affected.
Moderate to major flooding is predicted with heights set to rise on the Richmond, Hawkesbury-Nepean, Colo and Weir Rivers as well as Wollombi Brook.
The BOM has observed renewed rises on multiple rivers and warns that flooding may reach levels similar to the past week.
Heavy rain is expected from the Hunter through the Central and Southern Tablelands and down to the South Coast, with more rain on the Mid-North Coast on Monday.
Thunderstorms could also bring intense rain to the Northern Rivers, with damaging winds and large hail a concern in an area trying to clean up from devastating floods in Lismore and nearby towns.
Some areas could receive up to 120mm of rain in six hours and dangerous flash flooding could follow.
Six deaths have been confirmed in NSW, four of them in Lismore, from flooding that began over a week ago.
State and federal leaders have promised more help and financial aid as some affected areas begin the long cleanup, while other parts remain under water.
Mr Toole told AAP that NSW had called for defence assistance and he understood there were 5000 members available.
"We'll take every one of them. We can't delay ... we need them right now," Mr Toole said.
He said the devastation had left a smell "you just can't describe".
The "number one priority" for the state government was securing temporary housing for flood victims.
In Coraki, on the Richmond and Wilson Rivers south of Lismore in the Northern Rivers region, the local police station was one of many buildings inundated as the town was flooded and cut off from surrounding areas.
As waters recede, the damage is now being assessed.
Coraki Police Sergeant Dean Childs says the town had little chance to prepare for the floods.
"It happened that quick and no one expected it to be that high," Sgt Childs said.
With only a small number of emergency service personnel in Coraki, community members had to step in too.
"It's a smaller SES so we only have a certain number of boats, so we've got all these local people jumping in their own vessels to try and rescue people as well," Sgt Childs said.
While the community response to the disaster has drawn much praise from the state's politicians, there has also been criticism of the government's response and level of preparedness that required communities to rescue and look after one another.
Opposition emergency services spokesman Jihad Dib said on Sunday flood-hit communities are exhausted and people are now "at absolute breaking point".
"The local communities and people from outside of those local communities are doing all that they can, but they can't carry the full load by themselves," he said.
Premier Dominic Perrottet on Saturday pledged his government would not "spare a dollar" in funding the recovery.
The Insurance Council of Australia said claims in NSW had reached an estimated $250 million by the end of Friday.
Over the weekend the federal government expanded the local government areas able to access one-off disaster relief cash payments of up to $1000 for adults.
Australian Associated Press
