About 25,000 people have been told to evacuate as a cyclone carrying winds up to 240km/h (150 mph) moves towards the Queensland coast.
Cyclone Debbie is expected to intensify into a Category 4 system before it arrives early on Tuesday local time.
Some people have refused to leave despite warnings the destructive core could be as wide as 100km (62 miles), reports BBC.
Queensland Premier Annastacia Palaszczuk said the storm would rival the devastating Cyclone Yasi in 2011. Late on Monday, Ms Palaszczuk urged 25,000 residents in low-lying areas of Mackay to immediately find safer ground. More than 5,000 other Queenslanders were already evacuating their homes.
The cyclone is expected to make landfall sometime after 07:00 on Tuesday (20:00 GMT Monday) anywhere in a 265km zone from Townsville to Proserpine.
“That is the uncertainty of cyclones,” said Bureau of Meteorology regional director Bruce Gunn.
Authorities warned the cyclone could coincide with high tide, which is expected to peak at 3.2m. The storm surge could add an additional 4m, Ms. Palaszczuk said. She said this would bring the dangerous risk of flooding, especially around Mackay.
“I am just pleading to everyone, please, listen to authorities,” she said.
“I do, you must as well. This is about your safety, it is about the safety of your family and the safety of your children.”
Police Commissioner Ian Stewart said the weather contributed to the death of a woman, believed to involve a tourist, in a car crash.
Queensland authorities have closed 102 schools, 81 early childhood education centers and two ports. All flights have been canceled at Townsville Airport and Mackay Airport.
Prime Minister Malcolm Turnbull said the Australian Defence Force would help with the cyclone response.
“Time and time again, Australians show grace under pressure, bravery in the face of danger, and rally without a second thought to help each other,” Mr Turnbull said in parliament.
“These virtues will be on display over the next few days where Australians face the worst that nature can throw at us.”