PARTS of Brisbane and Ipswich will flood but the levels will not be as devastating as they were in 2011, authorities say.
If current projections play out, 3600 residential properties will be affected in Brisbane and of those, 2100 are unit dwellings where only ground floor flooding is expected.
About 1250 business properties are also expected to be affected in Brisbane while about 50 homes are projected to be inundated in the Ipswich suburb of Goodna.
Queensland Premier Campbell Newman says flood peaks would be much less than what was experienced in 2011.
Brisbane is expecting a 2.6 metre flood peak, nearly half of the 4.46m peak in 2011.
The Ipswich peak is expected to be five metres less than the 19.4m level in 2011.
"There will be flooding but the flooding is much much lower than what we saw in 2011," he said.
Mr Newman said the projections were based on the best scientific modelling by forecasters.
There would be minor floods in the Brisbane River, and in the Bremer River that flows through the city of Ipswich to the west of Brisbane.
"The peak of any flood will occur in Ipswich we believe around midnight (AEST) tomorrow (Monday) night," Mr Newman said.
"Similarly the peak at the western side of the Brisbane City Council boundary will be about midnight on Monday night."
Moggill is projected to be the first Brisbane suburb to be flood-affected on Monday afternoon.
Mr Newman said flood maps would shortly be released by the Brisbane and Ipswich councils, showing lists of affected suburbs.
The worst of the projected flooding would be seen further downstream around noon on Tuesday, with another peak expected at noon on Wednesday.
"If it doesn't occur, then I'm sorry in advance," the premier said.
"We want to give the communities in Brisbane and Ipswich, on the Brisbane and Bremer rivers, the best possible information as soon as it is available."
He urged people not to panic, but to check the flood maps and to prepare if they were in an area that may flood.
Mr Newman said there was flooding in the Lockyer Creek and the Bremer River which fed into the Brisbane River downstream from the Wivenhoe dam.