More than 14,000 properties are without power due to heavy rain from Tropical Cyclone Jasper.
Hundreds of people have been evacuated in northeastern Australia after extreme flooding cut off towns and forced residents to flee to rooftops to escape rising waters.
More than 300 people were rescued in Queensland state overnight, with military helicopters deployed to deliver supplies to areas cut off by the floods, officials said on Monday.
Cairns, a popular tourist destination that serves as a gateway to the Great Barrier Reef, has been almost completely cut off by flooding amid fears the city's 160,000 residents will soon no longer have access to clean drinking water.
Local officials said the city received about 600 mm of rain in 40 hours through early Monday morning, more than three times the December average.
All flights to and from Cairns Airport, with plans partly swamped by flooding, were canceled or postponed on Monday.
According to authorities, more than 14,000 properties across the region are without power.
In Wujal Wujal, a rural community in the Cape York region, nine people, including a seven-year-old boy, sought shelter on the roof of a hospital.
Crocodiles were spotted swimming in floodwaters in several rural areas including Wujal Wujal and Ingham.
The flooding is due to heavy rains and strong winds caused by Tropical Cyclone Jasper, which hit Australia last week.
Queensland state premier Steven Miles said the flooding was the worst natural disaster he had ever seen in the state.
“The problem is the rain won't stop and we can't get air support to remote locations until it lets up,” Miles told the Australian Broadcasting Corporation.
Queensland Treasurer Cameron Dick warned the disaster would have a “billion-dollar impact” on the state.
Weather authorities have predicted further rainfall on Monday as Jasper is expected to linger over the region.
Prime Minister Anthony Albanese said the Australian military had been placed on standby for rescue and relief efforts.