The New South Wales emergency services, which assisted 22 people overnight from Monday to Tuesday, called on some 50,000 people to evacuate.
Flooding, heavy rainfall and strong winds have caused power cuts to some 19,000 homes.
Australia is particularly affected by climate change, regularly hit by droughts, devastating forest fires, not to mention repeated and increasingly intense floods.
“Sydney is not out of danger, now is not the time to slack off,” said Carlene York, the state’s emergency services chief.
New South Wales Premier Dominic Perrottet called on people to comply with evacuation orders, saying “this event is far from over”.
The federal government has declared a state of natural disaster in 23 flooded areas of New South Wales, releasing aid for affected residents.
These heavy rains fell on an already partly soggy ground which caused a rapid rise in water levels, especially in the western suburbs of Sydney.
Many residents affected by this new meteorological episode had already been victims of the successive floods on the east coast which, in 2021 and March, killed more than twenty people.
“It’s so sudden, you can’t even get out that fast, you can’t even move anything,” Jenny Lee, a resident of Shanes Park in Sydney’s western suburbs, told AFP.
In the western suburbs of Windsor, Tyler Cassel hastily left his house in a canoe.
“The water came up very quickly, faster than usual,” he told Australian broadcaster ABC.
“This is one of the most terrifying floods I have experienced.”
Most of the affected areas are downstream of the Warragamba Dam, west of Sydney, which overflowed. It provides most of the city’s drinking water.
The rain has eased off in parts of Sydney, but flood warnings are likely to persist for several days, said Jane Golding of the state’s weather service.