The battered city of Bundaberg is bracing for one of its worst floods in history as it bears the brunt of ex-tropical cyclone Oswald.

One man is confirmed dead and hundreds of homes and businesses are expected to be inundated on Sunday night as the Burnett River rises towards a peak not seen in the central Queensland town in over a century.

Premier Campbell Newman says at least 300 homes and 100 businesses in Bundaberg will be inundated if the flood peak on Sunday night eclipses the 2010/11 level, as it's expected to do.

Bundaberg Regional Council Mayor Mal Forman says about 40 homes have been flooded and the army has been called in to help evacuate people.

He says Burnett River will peak at 8.5 metres on Sunday night, well above the 7.92m peak of 2010/11.

It will reach a second peak of 9m on Tuesday, when water from the catchments flows downstream.

The only other time on record a flood peak reached 9m was in 1893-94, meaning the town was heading into unknown territory, Mr Forman said.

"It's going to challenge us. It will be our greatest challenge," he told AAP.

"We do ask people to have patience and let us do our job and hopefully we can all get through it with the least amount of damage and hurt."

About 460 people are already in two evacuation centres with many more fleeing to relatives' homes on higher ground, while about 150 businesses have also been evacuated.

Two defence force Blackhawk helicopters are flying in from Townsville to help.

Residents are being told to prepare to spend several nights away from their homes.

Meanwhile, the body of an elderly man was found in the tornado-hit coastal town of Burnett Heads, northeast of Bundaberg, on Sunday morning.

Police said he had fallen overboard from a yacht which had broken from its mooring.

On Saturday afternoon and evening five tornadoes ripped through the coastal region near Bundaberg, injuring more than a dozen people and damaging 250 homes.

Two people were critically injured when a giant pine tree fell on their parked car on the Esplanade at Bargara, and about a dozen more were injured by flying glass and other debris.

Two homes were completely destroyed in the mini-cyclone that struck Burnett Heads.

Community Safety Minister Jack Dempsey, whose electorate takes in the tornado-struck region, said shell-shocked locals told him the tornado sounded like a jet landing and afterwards it looked like a bulldozer had ploughed through the area.

"When the force hit the Esplanade in Bargara it wasn't just smashing things, it actually sucked the air out of the buildings and blew out the windows," he told AAP.

Premier Campbell Newman visited Bundaberg on Sunday morning as part of a tour of disaster-hit regions and later told a press conference of meeting a couple whose home, caravan and car had been significantly damaged.

"My heart goes out to them," he said.

Residents have been warned sewage will be present in floodwaters because the council's sewerage pump stations aren't operating.