Brisbane to be lashed by massive storms

Queenslanders have been warned to prepare for the worst with flash flooding now a serious concern across the state.

Southeastern Queensland can expect about a month's worth of rain over the next 24 hours as ex-tropical Cyclone Debbie moves down the coast.

"As the low tracks down the coast towards Brisbane we can expect falls of up to 200mm or more in southeast Queensland," a BoM spokesman told AAP.

The Darling Downs, Granite Belt and Wide Bay region can also expect a lashing.

Police Commissioner Ian Stewart urged Queenslanders to stay inside and not to underestimate the dangers of the heavy rainfall.

"We saw what happened five or six years ago when we had the summer of disasters," Commissioner Stewart said.

He encouraged parents to pick up their kids from school early before the worst of the rain hits.

Education Queensland have closed all schools in the southeast of the state.