Floodwaters were slowly subsiding but more than 20 emergency warnings remained in place, with the focus shifting to assessing properties and delivering supplies to cut-off communities.

NSW emergency authorities estimated up to 10,000 properties had been damaged by flooding, mostly in central and northern parts of the state.

Many communities were still isolated, with 50,000 people estimated to be impacted, NSW State Emergency Services (SES) said.

"We will continue to resupply those isolated residents by land, water and air as part of our multi-agency response," SES Chief Superintendent Paul McQueen said.

"We ask you to be patient, remain in a safe location and please don't be tempted to drive through floodwaters or go sightseeing."

The death toll stood at five after the body of a man in his 80s was found at a property near Taree, one of the worst-hit towns.

Prime Minister Anthony Albanese was unable to visit Taree, as planned, because of treacherous access.

"Conditions remain critical with flood and evacuation warnings in place," Albanese said on X.

"We're continuing to work closely across federal, state and local governments to make sure Australians get the support they need now and through recovery."

More than 600 flood rescues were carried out over the previous three days, prompting NSW Premier Chris Minns to praise the work of emergency services.

"We would have had hundreds of deaths if it wasn't for the bravery, the courage of emergency service workers in the last 72 hours," he told journalists.

SES deputy commissioner Daniel Austin said he expected the number of warnings to decrease over the weekend but urged motorists to avoid driving in floodwaters.

He said stagnant water posed a health risk and that vermin and snakes could make their way into homes.

The storms dumped more than six months' worth of rain over three days, according to the government weather bureau, smashing records in some areas.

Although difficult to link to specific disasters, scientists warn that climate change is already fuelling more extreme weather patterns.