A second storm cell is forming off the New South Wales coast which is expected to bring further destructive gale-force winds and flash flooding.
Sydney and the NSW Central Coast have been ravaged by “cyclonic” conditions, with reports of homes and animals being washed away in floods.
A severe weather warning remains in place across the state, with waves still measuring up to 10 metres high.
The storm will ease throughout Wednesday as it moves southwards along the coast, but is still expected to dump a further 100mm of rain and bring gale-force winds.
Premier Mike Baird pleaded with residents to avoid driving through floodwater, and told those affected to “hang tough”.
“We’ll still have a lot to get through over the next 48 hours,” he said on Wednesday morning.
Mr Baird said parts of NSW would be declared natural disaster areas, with those affected eligible for financial assistance.
While conditions have begun to abate, parts of Sydney’s northern beaches remain on alert, with floodwaters expected to rise.
There are also fears of a landslide in Kiama, south of Sydney.
A Severe Weather Warning remains in place for an intense low pressure system situated over the Hunter location…. http://t.co/02Ej3peOWc
— NSW SES (@NSWSES) April 21, 2015
Manly residents were also warned overnight they may need to evacuate with Manly Dam at risk of overflowing.
The State Emergency Service has responded to more than 8,000 calls for help, while electricity providers have worked around the clock to restore power to more than 200,000 homes.
Mr Baird took to Twitter to urge Sydneysiders to stagger their peak-hour travel to work with public transport and roads already under immense pressure.
A large number of public schools will remain closed on Wednesday – a full list can be found here.
To ease strain on transport/road networks please again try to travel to work outside standard peak times – I urge employers to be flexible. — Mike Baird (@mikebairdMP) April 21, 2015