Brisbane Lord Mayor Adrian Schrinner has told residents fearful the city is on the verge of a major flood that the situation this weekend is "different" to the devastation of 2011.
Four people have died in floodwaters and hundreds of Gympie residents have been told to evacuate as an extreme weather system continues to dump flooding rain across south-east Queensland.
The Lord Mayor said the council's latest flood modelling showed overnight flows combined with possible Wivenhoe Dam releases and a high tide could result in water entering several thousand properties in the city.
The figure was an estimate and included situations where floodwater enters yards, but not necessarily homes, he said.
Residents in low-lying areas were told to be prepared, stock up on sandbags and household essentials and know when it was time to leave.
The suburbs the modelling indicated could be impacted are Brisbane City, Bulimba, Hamilton, Milton, New Farm, Newstead, Norman Park, Oxley, Rocklea, South Brisbane, St Lucia, Teneriffe, Toowong, West End, Windsor and Yeronga.
Speaking to announcer Cathie Schnitzerling on ABC Radio Brisbane before revealing the modelling, Mr Schrinner said it was "understandable" that people are reliving the Brisbane 2011 floods.
However, he said the weather system hovering over south-east Queensland was not the same as the one that caused havoc 11 years ago.
"It wasn't actually raining when the floodwaters came up," Mr Schrinner said.
"We've had an extraordinary situation now where we've had almost half a year's worth of rain in the last 48 hours and a lot of that has been concentrated over Brisbane and south-east Queensland. So that's an extraordinary amount of rain and it's still continuing to rain.
"The waters, they rise up quickly and they're often going down quite quickly but then we get more rain, so it's a different situation.
"I guess what we're all waiting to see is what happens with the dam management and the state authorities managing those."
Mr Schrinner said just a few months ago his council was "thinking we'd be moving into a significant drought management situation".
"Now, most of the dams are full," he said.
"People need to be reassured that all people across all governments have learned a lot from the past ... they've learnt a lot and they're working really well together."
Waterways around Brisbane were expected to experience a high tide at 6pm tonight and about 7am tomorrow morning.
Mr Schrinner said the combination of heavy rainfall and high tides meant more roads may become flooded this evening and Sunday morning.
Water released from dams, public transport services affected
Wivenhoe Dam was at 112 per cent of capacity on Saturday. At the start of the week the dam was at 56 per cent of capacity.
Seqwater said releases were being made from North Pine, Wivenhoe and Somerset dams.
Mr Schrinner also warned Brisbane residents to stay at home and resist the urge to go "sightseeing" in their neighbourhood.
"People should be staying off roads where possible," Mr Schrinner said.
"Do not go through floodwaters — you do not know what's under there, you do not know how deep it is."
CityCat services have been suspended along the Brisbane River due to the amount of debris on the waterway.
Bus routes 215, 220, 227, 590, 598 and 599 have also been temporarily suspended due to flooding.
Brisbane City Council has given out 20,000 sandbags since 3pm Friday and more are available outside SES depots at Darra, Morningside, Newmarket and Zillmere.
For non-life threatening emergencies, phone the SES on 132 500.
In an emergency, call triple-0.
