Thousands more residents were ordered to leave their homes in Sydney on Tuesday as torrential rains worsened the flood crisis in the city with rivers rising above danger levels.

The storm battering Australia’s eastern coast has now brought a year's worth of rain in three days to some areas which many attribute to global warming.

About 50,000 residents in New South Wales, most in Sydney's western suburbs, have been told to either evacuate or warned they might receive evacuation orders, up from Monday's 30,000, according to a Reuters report.

"This event is far from over," New South Wales Premier Dominic Perrottet told reporters. "Wherever you are, please be careful when you're driving on our roads. There are still substantial risks for flash flooding."

Prime Minister Anthony Albanese, who returned to Australia Tuesday after a week-long trip to Europe, said he would tour the affected regions on Wednesday along with Perrottet.

The federal government has declared the floods a natural disaster, helping flood-hit residents receive emergency funding support.

The latest wild storm cell – which brought a year's worth of rain in three days to some areas – is likely to ease in Sydney from Tuesday as the coastal trough moves north, the Bureau of Meteorology (BoM) said.

But the risk of flooding could remain through the week with most river in spate. Some regions have received over 31 inches) of rain since Saturday, which has surpassed Australia's annual average rainfall of around 20 inches.

Winds up to 90 km per hour are also forecast in several flood-hit places, raising the risk of falling trees and power lines.

Meanwhile, emergency crews are also grappling a rough sea in a rescue operation on Tuesday to tow a bulk carrier ship that lost power off Sydney's coast.