Queensland's major cities are in damage control mode as waters continue to rise.
At least one person has been confirmed dead and three others are missing as heavy rains and strong winds lash the region.
The east-coast city of Bundaberg is bracing for its worst floods in history, with officials saying around 1,200 properties are already flooded.
Bundaberg, which has a population of 98,000, is 385 kilometres north of the state capital Brisbane.
Deputy Mayor David Batt told ABC radio on Monday that hundreds of people need to be evacuated from their homes.
Queensland State Premier Campbell Newman says emergency crews are trying to rescue 30 people trapped on roofs in city.
In Ipswich, around 40km west of Brisbane, Mayor Paul Pisale is bracing for the worst, saying that after the deadly 2011 floods it's a case of déjà vu.
“I know I’m finding it very hard to deal with the emotional stress this morning, just talking with people,” he says.
“They’ve worked their guts out to get to this situation and now [ex-cyclone] Oswald’s come around and just kicked them in the guts – it’s very, very hard emotionally for me to feel, as you can imagine, what my community’s feeling at the moment.”
Deputy State Emergency Services Commissioner Steve Pearce says they've received more than 700 calls for help, and in some cases, rescuers are being forced to put their lives on the line because of foolish behaviour.
“The majority of flood rescues are [of] people attempting to drive through flooded roadways or causeways – so it’s people just rolling the dice, which is really concerning obviously,” he says.
While the water peak is not expected to reach the levels seen in the devastating Queensland flood two years ago, 5000 homes are expected to be inundated.
The tail end of ex-cyclone Oswald is due to hit Sydney tonight.