Tropical Cyclone Alfred is expected to make landfall late on Thursday or early Friday somewhere between Queensland's Sunshine Coast and the Gold Coast, according to the Bureau of Meteorology.
The danger stretches far further afield and wild weather is tipped to start up from Wednesday, with the warning zone from Double Island Point in Queensland to Yamba in northern NSW, south of Byron Bay.
It's set to bring flash flooding, heavy rain, destructive winds and storm surges at its height, with southeast Queensland facing its first direct cyclone impact in 50 years.
"Several hundreds of millimetres of rain is possible within six hours, which could lead to life threatening flash flooding," the bureau's senior meteorologist Christie Johnson said.
Brisbane the Gold Coast and Queensland hinterland are most at risk of copping the brunt of the strong winds while residents in NSW's Northern Rivers have been told to stay inside and secure anything that could blow away.
After sandbagging their home, Roxanne Zolin and partner Pierre D'Aubbonnett have been putting the finishing touches on their cyclone preparations before leaving.
The couple had planned to bunker down at their Bribie Island residence north of Brisbane, with gale force winds and heavy downpour expected from Wednesday.
Instead they will go to the mainland and ride out the storm at the rural town of Toogoolawah.
Alfred marks the couple's first extreme weather event on the island and they are worried.
"We're so close to the water you can see it," Ms Zolin told AAP.
Sandbags fortify their home and tape is strewn over their windows, including their beautiful stained glass front doors, but there is still much to prepare.
"I've been trying to get rid of all the pot plants off my front porch because I can imagine the wind picking them up," Ms Zolin said.
Mr D'Aubbonnett is so concerned about downstairs flooding he has been taking photos of beloved items before they head off, keeping his fingers crossed they remain intact.
The prime minister has touched down in Brisbane, as the federal disaster response plan activates and a crisis co-ordination team deploys.
Queensland Premier David Crisafulli said the cyclone had firmed and was urging people to follow the advice of emergency personnel.
"This is a very rare event for southeast Queensland, but it's not unprecedented, and we are asking you to take it seriously," he said.
Schools remain open in Queensland on Wednesday but beaches, university campuses and Gold Coast theme parks will close along with ferry services.
Flights are likely to be affected.
Emergency services, telco providers and Energex crews have bolstered the region with evacuation centres on the Gold Coast open.
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