Gympie Regional Council Mayor Ron Dyne said that "extreme rainfall" overnight flooded creeks and some homes.
But he says the flooding will not be as bad as that which devastated most of southeast Queensland in January last year, so long as the Mary River does not overflow.
Earlier, a father and son stranded on top of their car were plucked to safety from racing floodwaters at Tiaro. The pair, aged 26 and 65, waited more than three hours before two crews in flood boats were able to retrieve them.
In New South Wales, almost 5000 people have been forced to flee their homes while others have been placed on high alert as water levels continue to rise.
Nine more local government areas have been declared disaster zones.
The Riverina region, in the state's southwest, has become the focus for emergency services, with the Murrumbidgee River bursting its banks.
Downstream at Gundagai, about 60 people have been evacuated with 30 homes, businesses and the local racecourse flooded.
- AAP