Southeast Queensland remains on alert after severe floods and tornadoes have devastated the state in the last 24 hours, leaving up to four people dead and another two missing.
The army has been called in to assist with the floods as the area braces for a heavy deluge.
Floodwaters are expected to inundate thousands of homes and businesses in Brisbane and Ipswich this week, but authorities have stressed it will not be a repeat of the devastating floods in 2011.
Floods are also expected at Gympie and Maryborough.
Emergency Services say the worst of the weather for Sydney is expected to arrive this evening between 5pm and midnight, bringing huge winds, heavy seas and flash flooding.
Further north, 500 homes in the New England Region have already been cut off by floodwaters.
And Steve Pearce, from the State Emergency Service, says it's not only the rain that's causing problems.
“With these winds that have been generated from Cyclone Oswald, and everyone’s seen those tornadoes in Queensland, we’ve now got a forecast of destructive winds for our northern rivers, of up to 140 km/h which are really enormous destructive winds.”
An 81-year-old man was the first person found dead in waters at Burnett Heads, near Bundaberg in Queensland.
Also believed dead are a woman who was last seen driving through floodwaters, a person on a boat and a disabled man in a car with his parents. The parents managed to escape, but he was swept away with the vehicle and is presumed drowned.
Thirteen hundred people in northern New South Wales have found themselves isolated by floodwaters.
The Brisbane River is expected to peak tomorrow afternoon, and again on Wednesday. Any flooding that occurs isn't expected to be as bad as 2011, though around 3600 properties are at risk, including 1250 businesses.