Qld flood threat eases but more rain due

Queensland's flood threat has finally eased after another 24 hours of torrential rain caused widespread chaos in the southeast but the respite will be brief.

With dozens of swift-water rescues carried out, hundreds of roads under water, schools closed, and residents on evacuation alert, the Queensland premier has warned of more heavy downpours and a possible cyclone.

Ms Bligh on Wednesday said the state was in the first part of a three-phase weather event and about to enter a relative lull.

Phase two was likely to hit late on Friday or Saturday and continue to Tuesday, the result of a monsoonal trough that has been affecting the north, she said.

"It could see widespread falls of 200mm to 300mm over a couple of days," the premier told reporters in Brisbane.

The third phase could see the formation of a cyclone in the north or far north of the state, she added, but there was nothing to suggest it would cross the coast.

The warning came as Brisbane copped between 200 and 300mm of rain in the 24 hours to noon on Wednesday (AEST), and the Gold Coast was drenched with between 100 and 115mm in six hours on Wednesday morning.

The deluge came on top of similar heavy falls on Tuesday.

Firefighters have carried out 26 swift-water rescues since noon (AEST) on Tuesday after dozens of motorists became trapped in floodwaters.

In the same period the State Emergency Service received 1076 calls for help, mainly for leaking roofs and requests for sandbags.

Rescuers used a boat to save a family of four when their car became trapped in rising water at Tabragalba, south of Brisbane, at about 10.45am (AEST).

And two women were found safe on Wednesday after their car was swept off Old Gympie Road in the Glasshouse Mountains, in the Sunshine Coast hinterland, on Tuesday night.

Residents of 25 homes and a caravan park on the Gold Coast narrowly avoided having to evacuate after Loders Creek at Chirn Park subsided and a storm warning was cancelled.

Twenty-five schools and 30 childcare centres around the southeast were shut because of flooding, with most closures occurring in the region south of Brisbane and on the Gold Coast.

Premier Anna Bligh said Seqwater had started releasing water from Brisbane's biggest dam, Wivenhoe, under a new management policy implemented after last year's floods.

The dam is 76 per cent full and water is being let out at 350 cubic metres per second, far below the 7000 cubic metres per second released during last year's floods.

Memories of January 2011 are still haunting many residents and police have fielded numerous calls from anxious flood victims, the premier said.

The deluge has also put a dampener on Australia Day festivities in the southeast, and events scheduled for Brisbane, Ipswich and the Moreton Bay Region have been cancelled.