The flood threat along the New South Wales mid-north coast has eased, but thousands of people have been left isolated.
Flood warnings are in place for 15 river systems from Sydney to the Queensland border.
Two people are confirmed dead as a result of the flooding, caused by a slow-moving low pressure system that has made its way down the eastern coast over the past few days the ABC reports.
In Kempsey floodwaters flowed over the levee protecting the town centre after the Macleay River reached its peak.
Some water made its way into low-lying areas of the CBD, but water levels in the town are now falling.
The majority of businesses in the town are closed and have been sandbagged.
About 10,000 people are now isolated in the Macleay Valley, including the coastal towns of Crescent Head and South West Rocks.
Further south in Port Macquarie, the Hastings River also broke its banks, flooding low-lying homes and businesses in parts of the CBD and along the riverfront.
State Emergency Service spokesperson Phil Campbell says many people near Port Macquarie had to leave their homes for higher ground.
Evacuation warnings are in place for low-lying areas of Taree, Cundletown and Wingham.
The SES has received more than 4000 calls for help across the state.
About 500 of those came from Sydney, after torrential rain and strong winds tore down the coast on Sunday morning.
Thousands of people are without power, and dozens of homes have been damaged in Malabar, Narellan and Kiama.
On Saturday, about 100 passengers were trapped on a train for nearly 17 hours in the wild weather. The train journey from Sydney to Casino was halted three times, by fallen trees on the line, floodwater and finally a landslide.