Residents are being evacuated from parts of northern New South Wales as the discovery of a man's body raises the death toll to two.
Evacuation orders are in place in several towns along the mid-north coast, including Kempsey, Port Macquarie and Bellingen, and emergency services are asking people not to enter floodwaters.
Major flooding is continuing around Port Macquarie, particularly downstream at Wauchope where the Hastings River peaked at 7.2 metres on Saturday evening.
There are as floodwater from a low-pressure system continues to hit the region.
The SES's Alison Richards says affected residents near Port Macquarie should leave immediately. An evacuation centre has been set up in the Port Macquarie town centre.
"We are concerned that the river is rising quite quickly," she said.
"We are expecting a peak later tonight of 1.9 metres at Settlement Point. This is regarded as a major flood level."
Some businesses in the Port Macquarie CBD are being sand-bagged.
The SES also predicts Bellingen may experience the worst flooding it has seen in years, and evacuation orders have been issued for lower parts of the catchment.
More than 16,000 homes are without power from Byron Bay to Taree.
The flood warnings come as SES volunteers discover the body of a man in a submerged car north of Grafton at 1:00pm (AEDT).
Police say they have retrieved the body of the man, but the car remains stuck in floodwater.
The discovery takes the death toll to two after 17-year-old Luke O'Neill, from Bonny Hills, drowned after being swept into a stormwater drain south of Port Macquarie.
He had been waist-deep in floodwater collecting golf balls with two friends at the Camden Haven Golf Course at Kew during the height of yesterday's storm.
A force of water trapped him in a large drainpipe. He drowned and his body was found this morning at a dam about 40 metres away.
Another boy, aged 16, was sucked into the drain while looking for his friend.
He is being treated at Port Macquarie Base Hospital with water on his lungs.
Mid-north coast police inspector Kim Fehon says it is a clear warning for others.
"The most important message with the terrible weather that we are having at the moment is for all people to stay away from water-affected areas," he said.
"This was a tragic outcome and we really don't want it to happen to anyone else."
Further north, near Coffs Harbour, a Glenreagh mother and her five children have managed to escape rising floodwaters.
The family called the SES for help this morning when their home became swamped.
Overnight on Friday due to fallen trees and a landslide.
Passengers had to wait it out for 17 hours while earth-moving equipment cleared the tracks and allowed the train to return to Coffs Harbour.
A destructive low-pressure system has been moving through the region, keeping emergency crews busy.
At least 330 millimetres of rain was dumped on some parts of the Bellinger River catchment, near Coffs Harbour, overnight.
The State Emergency Service says the river has peaked near record levels set in 1974.
Major flooding is also expected for the Orara River west of Coffs Harbour and the Hastings River near Port Macquarie.
Evacuation orders have already been initiated for lower parts of the Bellinger River catchment, and evacuation centres have been set up at Bellingen and Urunga.
The Macleay River at Kempsey is expected to exceed 6.4 metres today.
The Hastings River is expected to peak at 10:00pm tonight, causing major flooding.
The Clarence River is expected to peak early tomorrow morning at Grafton at around 5.6 metres.
Sam Colwell from the Clarence-Nambucca SES says it is not expected to be as bad as the floods three weeks ago, but low-lying areas are being watched closely.
"Ulmarra, Brushgrove and Cowper are areas that are low-lying and they do get affected and isolated quite easily," she said.
"We are certainly keeping a close watch on the Clarence to see what effect it's going to have in those particular areas.
"We just want to make sure that people are alerted early on and that way we can get them to prepare their homes."
The severe weather system is now tracking south and slowly weakening.
In Ballina, a big clean-up effort is underway after winds of up to 230 kilometres an hour lifted roofs from the town's bank, real estate agency and child care centre.
The winds brought down trees and power lines across the region, and power is still out to over 30,000 people.
Ballina Shire Council general manager Paul Hickey says sewerage and water systems are also out of action.
"[There's] a lot of pressure on the sewerage system with the influx of rain.
"So we've got pump-out trucks and other staff out helping. I'd encourage people to minimise their water use and sewerage use (this morning)."
© ABC 2013