Queensland Premier Anna Bligh has warned residents in the north of the state it is too late to evacuate ahead of Cyclone Yasi.
After the worst floods in the state's history, Queenslanders are being told to brace for a catastrophic storm.
Parts of the state are beginning to feel the impact of Yasi, now a maximum-strength Category 5 system, with winds estimated to peak at 300km/h.
The cyclone is due to cross the coast between Cairns and Innisfail, about midnight local time on Wednesday, Australia's Bureau of Meteorology says.
Wind gusts have been buffeting parts of Cairns, while further south the wind has also picked up in Townsville.
Ms Bligh said on Wednesday night that people in affected areas must shelter where they currently are as conditions are now too dangerous to travel in.
She says the state faces a cyclone of "catastrophic" proportions and a very large stretch of highly populated coastline is at risk.
Ms Bligh predicts it will be a very frightening time, with 24 hours of terrifying winds, torrential rain and the likely loss of electricity and mobile phones from Wednesday afternoon.
The Bureau of Meteorology says Cyclone Yasi is likely to be more life-threatening than any storm in recent generations.
Winds are expected to reach more than 150km/h by early on Thursday and a storm surge of up to two metres is forecast to flood up to 30,000 homes.
Mines, railway lines, airports and ports have been shut down, with officials warning that Yasi could drive inland for hundreds of kilometres, hitting areas still struggling to recover from months of devastating floods.
More than 400,000 people live in the cyclone's expected path, including the cities of Cairns, Townsville and Mackay, which are also main tourist areas and take in the Great Barrier Reef. Island resorts in the Whitsundays have also been been evacuated.
Earlier, Yasi damaged weather monitoring equipment when it passed over Willis Island.
Thousands flee to shelters
More than 10,000 people are in shelters along the north Queensland coast and they could be there for days, the ABC reports.
Army ration packs are being distributed to evacuation centres in Cairns which were closed on Wednesday morning.
The State Emergency Service says people if people are still at home, they should be taking shelter in the safest and strongest parts of their houses, normally the bathroom or toilet area.
The mayor of Cairns, Val Schier, believes people are well prepared and not panicking. However, she says the lives of emergency workers will not be put at risk to rescue people during the storm.
The Australian Defence Force was called in to evacuate hundreds of patients from Cairns hospitals to Brisbane on Tuesday.
Bureau of Meteorology forecaster Andrew Carns, based in Townsville, says Yasi is likely to be one of the biggest cyclones on the Queensland coast in recorded history.