The storm that started as tropical cyclone Oswald just north of Australia was pulled south over most of the east coast by a low-pressure system extending all the way to New South Wales, Richard Wardle of the Bureau of Meteorology in Queensland said.
As it made landfall, Oswald lost its cyclone status but remained a "vigorous" storm, Wardle said.
In Queensland and New South Wales, the flooding occurred while bush fires that broke out two weeks earlier were still smoldering, and climate scientists said both the fires and the storms were "consistent" with climate change, NewScientist.com reported Tuesday.
"The frequency of more intense events is going to increase. Droughts, heatwaves and -- in northern Australia -- rainfall events and tropical cyclones are going to be more intense," said Jon Nott of James Cook University in Townsville, Australia, who researches extreme weather events.