Premier Annastacia Palaszczuk says life-threatening flash-flooding is under way and some rivers are still yet to peak, particularly in Logan and Gold Coast.

She said the Brisbane River is falling after peaking 3.85 metres on Monday morning, below the 2011 flood peak of 4.46m.

"It is still a significant event, and I think everyone would agree no one has seen this amount of rain in such a short period of time over our entire southeast catchment zone," Ms Palaszczuk told reporters.

"And I also want to extend my gratitude and thanks to the hundreds if not thousands of workers out there the SES crews, the police, our firies, our volunteers, all of the council workers."