The ex-tropical cyclone is on track to cross the coast on Saturday morning, with a severe weather warning issued for most of southeast Queensland and northern NSW.
"The category of a tropical cyclone is only dependent on the wind gusts so while the winds are backing off a little bit, the rain is still coming through in full force," weather bureau Senior Meteorologist Miriam Bradbury told ABC TV.
"We're still seeing widespread flash flooding, widespread impacts likely to continue through today and well into tomorrow as well."
Wild weather pummelled coastal communities overnight, with 120 millimetres of rain recorded at the Gold Coast and 130mm at Lismore since 9am on Friday.
Some 240,000 homes and businesses have lost power in southeast Queensland and thousands more have been warned to brace for ongoing outages.
Dozens of evacuation alerts have been issued for communities in northern NSW and the Lismore levee is expected to spill later on Saturday.
A man remains missing in floodwaters in Megan near Coff's Harbour after he was swept away by rushing water as he clung to a tree.
Brisbane cafe owner Quat Vu has spent days preparing and is as ready as he can be.
His Eightysix Cafe was inundated during the 2022 floods which devastated more than 20,000 homes and caused $2 billion in damage.Â
"We know what to expect and we had a bit more time to prepare," Mr Vu told AAP.
Blue translucent tarps line his brick cafe's windows, hunkered down with lines of yellow and white sandbags.
"We had (sandbags) to a certain height but then we got the latest news about what the cyclone is doing and how it is going to dump a lot more rain so we're just getting ready," he said.
It's a team effort across southeast Queensland, as neighbours and locals chip in to prepare for the wild weather.
"We're hoping for the best on Saturday," he said.
Significant impacts are expected from Double Island Point in Queensland down to Yamba in NSW.
"We're asking people to have a plan. That's the greatest thing you can have in this," Queensland Premier David Crisafulli said.
Those in NSW's northern rivers region face an anxious wait, with about 19,000 residents told to leave.
Prime Minister Anthony Albanese said a team of 66 disaster response personnel have arrived from New Zealand to assist, as hardship payments for those who are unable to work activate.
