On Monday, rescue workers said they had assisted more than 80 people since the evening before.
Thousands of Sydney residents were called to evacuate their homes, on the third day of torrential rains as overflowing rivers flooded land and torrents of water escaped from the main dam in Australia's largest metropolis.
The ground is saturated, rivers are flowing fast, dams are overflowing, said Carlene York, a state emergency services official.
About 32,000 people have been issued an evacuation order or warning in New South Wales, emergency services said.
Australia is particularly hard hit by climate change: the country is regularly hit by droughts, devastating wildfires and repeated and increasingly intense floods.
Many people were trapped in their cars trying to cross flooded roads or were stranded in their homes surrounded by rising water.
The suburb of Windsor, northwest of Sydney, has been hit hard by flooding.
Muddy waters had turned a large swath of land into a lake in the suburb of Camden on Monday morning, southwest of Sydney.
On television, footage showed roads that had disappeared under water and flooded mobile homes, including at least one overturned on its side.
Large volumes of water gushed from the pressurized Warragamba Dam, which supplies the majority of the city with drinking water.
Forecasters say torrential rains in New South Wales could persist for another at least 24 hours.
Off the coast of Sydney, rescuers attempt to rescue a 150-metre-long freighter with 21 crew members on board. A helicopter rescue operation had to be postponed for safety reasons, police say.
The east coast of Australia has suffered repeated flooding for the past 18 months.
In March, flooding caused by severe storms devastated western Sydney and claimed 20 lives.
< p class="e-p">As the planet warms, the atmosphere contains more water vapour, increasing the chances of heavy rainfall events, scientists say. These rains, together with other factors including land use planning, promote flooding.
Our research into the March 2021 floods in Sydney revealed that similar events over Sydney were likely to occur 80% more often by the end of the 21st century said Kimberley Reid, atmospheric scientist at Monash University. p>
Australia must prepare for more regular flooding, Dominic Perrottet, Premier of New South Wales, told a press conference.< /p>
There is no doubt that these events are becoming more frequent, he claimed. Governments must adapt and ensure that we respond to the changing environment in which we find ourselves.