The death toll rose to 10 after a woman believed to be in her 80s was found dead in a flooded property, police said.
The floods, which began late last week, flooded several cities and bridges in Queensland and New South Wales and moved south with torrential rains and possible flash floods to Sydney.
“This rather significant meteorological system … we will see it enter the central coast of Sydney and we are already experiencing elements of that at the moment,” said Prime Minister Scott Morrison during a press briefing.
Sydney, Australia’s largest city and home to more than 5 million people, could receive up to 150 mm (6 inches) of rain within six hours on Tuesday afternoon, the Bureau of Meteorology said. The average rainfall in Sydney for March is 138 mm, according to official data.
New South Wales Prime Minister Dominique Perottet described the extreme weather as “a one-thousand-year event” and said emergency services had made more than 1,000 rescues in the state, having received 6,000 emergency calls so far.
Hundreds of people are still stranded in their homes in the town of Lismore in northern New South Wales, facing the worst floods in history amid reports that some are spending the night on rooftops. Mayor Steve Krieg told Channel Seven that nine people are still missing and 400 rescue operations have not yet been carried out.
About 50 people were rescued after getting stuck on a bridge at night when fast-rising waters submerged both ends, authorities said.
Summer on the east coast of Australia is dominated by the climate model of La Nina, which is usually associated with higher rainfall for the second year in a row.
Brisbane, Australia’s third-largest city, has received about 80 percent of its annual rainfall over the past three days, Queensland Prime Minister Anastasia Palashchuk said on Tuesday.