Parts of Queensland's Gympie region are facing inundation for the second time in recent months, with the Mary River expected to reach its peak on Saturday amid the state's "evolving" weather event.
Authorities are warning Queenslanders the current weather event is not expected to be as severe as the flood event that swept the state earlier this year.
However, Premier Annastacia Palaszczuk told residents whose properties were flooded in February that they should be prepared and alert.
Gympie Mayor Glen Hartwig had previously said the peak would likely be close to 13 metres, but new forecasts place the peak at 16m.
Mr Hartwig said lower-lying businesses, including those in Mary Street, needed to prepare to evacuate for a second time.
The scale of this flood event is far below the one that devastated the town in February, when the river reached 23m and inundated 800 properties.
In the Southern Downs, up to 30 homes at Warwick were expected to be impacted by flooding when the Condamine River was expected to peak at 7.5m on Friday night.
Southern Downs Mayor Vic Pennisi said that while water was receding in some parts of the region, Warwick remained cut off by floodwaters.
"It's a moderate to major flood, but we've had worse," Mr Pennisi said.
More than a dozen emergency alerts have been issued across Queensland, from the North Burnett south to the border.
Emergency alerts for Gympie and Scenic Rim
Emergency alerts were issued by the Gympie Regional Council and Scenic Rim Regional Council on Friday amid warnings of dangerous flash flooding and road closures.
Ms Palaszczuk said the Ipswich Mayor had advised there was flooding in Rosewood, Grandchester and Mount Walker.
The Bureau of Meterology (BOM) said the Bremer River at Rosewood might peak near 6.4 metres on Friday afternoon.
BOM senior forecaster Laura Boekel said the situation was "evolving".
"Initially the predictions were that today we would start to see that easing trend … [but] that rainfall is likely to stay around today and into tomorrow," she said on Friday.
The Premier said, based on current forecasts, the rain event should not be "as severe as last time".
"This rainfall is actually more sporadic, and not as heavy," Ms Palaszczuk said.
"But we are still seeing some cases of flooding, and the river rising in particular areas.
Ms Palaszczuk said about 300 households in Laidley have had water on their properties and eight evacuation centres were opening.
The Lockyer Valley got 170 millimetres of rain in the 24 hours to 9am on Friday.
Major flood warnings issued for several rivers
Major flood warnings still remain in place for the Condamine River, Laidley and Lockyer creeks and the Logan River.
The Lockyer Creek was expected to remain above the moderate flood level of 10 metres on Friday afternoon.
Several bridges, roads and more than 20 business have been inundated by water in the Lockyer Valley region.
At least six water rescue crews had already been deployed to rescue residents from floodwaters in the region.
Ms Palaszczuk said the Brisbane River was not expected to reach beyond minor flood level.
She said dam levels across the south-east Queensland grid have gone from 89 per cent to 95 per cent in recent days.
The Wivenhoe Dam had hit 110 per cent, in February it was at 185 per cent.
"There's still plenty of flood storage available," Ms Palaszczuk said.
Ms Palaszczuk said there were controlled releases underway, but they would stop once rivers rise too high.
Hundreds of properties at risk
Lockyer Valley Mayor Tanya Milligan said modelling based on current predicted rainfall suggested up to 260 homes could be impacted or inundated in areas including Laidley and Grantham.
She said there was a minimum of 100mm of rain forecast for Friday and there was also the chance of storm cells.
"The modelling is even telling us, this is the really horrible stuff, there is an expectation we will probably have about 260 homes that will have inundation," Ms Milligan said.
"The event that we had in February and March we had about 68 homes [inundated].
The Queensland Fire and Emergency Service issued more than dozen emergency alerts overnight and this morning.
Warnings are also in place for Stanthorpe, Warwick, Scenic Rim, the Sunshine Coast, Gympie and North Burnett regions.
Floodwaters from the Condamine River have cut Warwick in half, with the bridge on the New England Highway closed.
The BOM predicted flood levels were likely to exceed the January 2013 flood level of 7.21 metres.
It predicted the Condamine River level might reach 8m by Friday evening.
More than 110 roads in the region have been impacted and 10 bridges are closed.
Laidley's town centre flooded on Friday morning, with rescue crews saying they were shocked at the speed waters rose through the main street.
Grantham flood warning sounded
The Lockyer Valley Regional Council said the Grantham flood siren had been sounded to warn residents in low-lying areas to get to higher ground.
The Lockyer Valley Regional Council told Grantham residents at about 5am on Friday to evacuate and not to wait for emergency services to doorknock.
"The siren is intended to prevent any loss of life and relies on the community heeding the siren," the council said in tweet.
Grantham resident Garry Godley said many locals evacuated the area after the siren sounded early on Friday morning.
"It took three days of raining and local flooding before it was activated,'' Mr Godley said.
"We have had about 40mm overnight — light rain with some heavy rain — but our problem is not the rain, it is all the water running off into Grantham from surrounding areas. It's what happened in 2011 and in February,'' he said.
Meanwhile, the Lockyer Valley Council said flooding at Laidley Creek Bridge had eased, after it broke its banks at Mulgowie, south-east of Grantham, on Thursday.
'An amazing community'
Business owner Letesha Dean has returned to her rural supply store in Laidley to assess the extent of the flood damage.
There has been at least a metre of floodwater running through her store.
"It's pretty stressful — we haven't owned the business that long — we only took over in October last year," she said.
"We had a few staff there moving stuff up for us and moving stuff out so we can try and save a few things."
Fifth-generation Laidley resident Debbie Northway has also been waiting out the floodwaters in her home.
"There has been some flood mitigation work, which assisted for a while, but once the Laidley Creek breaks its banks at Mulgowie, the water spreads across the farmland and into the town.
"The farmers can't keep losing their topsoil, farmland and crops.
"We need serious attention to the climate emergency, or farmers won't be able to feed the nation, no matter how heroic their efforts."