The Sydney Opera House in Sydney, Australia. Photo: Xinhua

Fresh evacuation orders were issued for tens of thousands of Sydney residents on Monday after relentless rains triggered floods for the third time in 2022 in some low-lying suburbs.

An intense low-pressure system off Australia's east coast is forecast to bring heavy rain through Monday across New South Wales after several places were hit with about a month's worth over the weekend.

Since Sunday, about 30,000 residents in New South Wales state have been told to either evacuate or warned they might receive evacuation orders.

Frustration swelled in several suburbs in the west of Australia's largest city after floods submerged homes, farms and bridges.

"It's just devastating. We are in disbelief," Camden Mayor Theresa Fedeli said.

"Most of them have just come out of the last flood, getting their homes back in place, their businesses back in place and unfortunately we are saying it is happening again."

More than 200 millimeters of rain have fallen over many areas, with some hit by as much as 350 millimeters since Saturday. 

Some areas could approach or exceed the flood levels seen in March 2021, and in March and April in 2022, the weather bureau warned. The risk of major flooding remained though the intense weather system may weaken later on Monday, it said.

An operation was underway to rescue 21 crew members from a cargo ship, which lost power south of Sydney and risked being swept ashore, local media reported.

"It has been a very difficult time for many months to have this flood event off the back of others. It makes it more challenging," New South Wales Premier Dominic Perrottet said.

Paul O'Neill, a resident from flood-hit Wisemans Ferry, said he was taking food supplies by boat to his stranded family after rising waters cut off access.

"The road collapsed and hasn't been fixed since the last floods, hasn't been touched. So now they close our road access and then the ferry, the only way to get home now is by boat," O'Neill told Reuters.

Footage on social media showed petrol stations, homes, cars and street signs partially under water while garbage bins floated down flooded roads. Military vehicles were seen going into flooded streets to evacuate stranded families.

About 100 millimeters of rain could fall in the next 24 hours over a swath of more than 300 kilometers along the New South Wales coast from Newcastle to the south of Sydney, the Bureau of Meteorology said.

The weather could trigger flash floods and landslides, with river catchments already near full capacity after the La Nina phenomenon, typically associated with increased rainfall, lashed Australia's east coast over the last two years.

Reuters