Rescuers in the flood-hit city of Bundaberg are battling to reach 30 people trapped on rooftops.
Premier Campbell Newman says it's been too dangerous to save those people, but efforts are continuing.
He said the flood in Bundaberg was expected to break all records, with water levels reaching 8.7 metres at 5am on Monday.
Mr Newman said the city was expecting a flood "well and truly beyond the formal record flood of 1942" and possibly bigger than a flood that wasn't properly recorded in the 1890s.
"There is quite a critical situation there at the moment with 30 people stranded on roofs," he told ABC News 24.
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"We're going to try and rescue those people this morning.
"Even though we have helicopters, the weather conditions are appalling and dangerous for flying. The floodwaters are very swift and it's also dangerous to go out in flood boats.
Mr Newman said there had been torrential rain in hinterland areas from Gympie to the south.
"Gympie is expecting a very significant flood and then downstream Maryborough is preparing as well."
He said the rainfall had been very heavy across the southeast overnight, and a lot more water than expected was coming into waterways that fed into the Brisbane River downstream of the protective Wivenhoe dam.
"I'm afraid we're going to see a lot more water coming down the Lockyer creek and the Bremer River than we expected," he said.
Mr Newman said water was currently being let out of Somerset dam, into Wivenhoe dam.
He said releases from Wivenhoe "backed off to allow for floodwaters that are going to come down the Bremer and the Lockyer to pass through Ipswich and Brisbane".
"So there is active management of those dams right now, to minimise flood levels," he said.
He urged Ipswich and Brisbane residents to consult flood maps, released by the two councils on Sunday, showing which streets were expected to inundate.
Mr Newman also said the Darling Downs town of Warwick was also expected to flood.
"Warwick will also experience a seven metre flood around midday today," he said.
"We believe 30 properties will be flooded there."
He urged Queenslanders to dig deep, as they did after the 2010/11 flood disaster, and donate money to a new flood appeal launched on Monday.