Forecasters predict central and southern Queensland will be worst hit by the latest deluge, which will last into the weekend.

In Rockhampton, however, waters are slowly starting to recede after the Fitzroy river peaked on January 5.

The town of St George is braced for the Balonne river to peak by Sunday.

About 1,200 homes across Queensland have been inundated since heavy rains set in last month, with another 10,700 suffering some damage, officials say.

Meteorologist Bryan Rolstone, quoted by Australian broadcaster ABC, said the latest rain would fall in the Wide Bay-Burnett region, affecting Rockhampton and the city of Bundaberg, which has also already suffered severe flooding.

Further south in St George, residents have filled about 10,000 sandbags and more were being prepared in an attempt to protect homes.

With natural disasters declared across an area of a million square kilometres, Queensland Premier Anna Bligh said the flooding was unprecedented in her state and had now directly affected 40 communities.

She said floods that have closed dozens of mines, railways and ports would send coal and steel prices soaring.

Queensland produces about half the world's coking coal used to make steel.