South-east Queensland is on alert for flash flooding on Monday morning.
The weather bureau issued a warning for heavy rainfall along the south-east coast, Wide Bay and Burnett and far southern Capricornia districts. Up to 200mm of rain were likely in 24 hours.
The Bureau of Meteorology said a combination of an upper level low and surface trough near the south-east coast is causing the instability.
However, senior forecaster Jonty Hall said conditions will not be anything like ex-tropical cyclone Oswald.
"It is likely to be raining fairly continuously, but the heavier falls will come in bursts on and off so it won't be particularly raining the whole time," he said.
"We could have the odd rumble of thunder with the heaviest stuff coming through, but thunderstorms aren't likely to be a big feature of this event."
The ABC reports extra water is being released from the dams in preparation for the rain.
Wivenhoe Dam west of Brisbane is 90% full. Its release rate will almost double to 280 cubic metres per second.
Colleges Crossing is likely to remain shut until the rain clears the dam catchments.
5000 calls for help in NSW
The State Emergency Service in New South Wales received more than 5000 calls for help after storms caused damage along the coast at the weekend.
Many of the calls came from Sydney and the Illawarra region
Two people are confirmed dead since Friday.
The Bureau of Meteorology said two heavy weather systems met in a narrow band along the east coast. The result was heavy rain and winds gusting close to 100km per hour.
The ABC reports swollen creeks and rivers are starting to recede in New South Wales, but around 20,000 people are likely to remain isolated for several days.