Thousands of more Sydney residents are being warned to expect evacuation orders this morning as the downpour continues in New South Wales.
Evacuation warnings are in place for 18,000 residents in low-lying areas including Londonderry, Clarendon and Wetherill Park in Western Sydney the Colo River area.
Authorities are particularly concerned about residents living near the Colo River. It is expected to peak at 16 metres late this afternoon or in the early evening.
The SES said roads are already cut by flood water and it will be using boats and helicopters to relocate people from the valley.
Once people are relocated to a safe place, transport and accommodation will be organised.
Forecasters are expecting 50mm to 100mm of rain to fall in the next 12 to 24 hours across many parts of NSW.
The BOM is warning of flash flooding bringing a serious risk to the whole northern and central coastal districts of NSW today, particularly in the Northern Rivers , Mid North Coast, Lower Hunter, Blue Mountains, and Sydney Metro regions.
It warns the extreme weather will be life threatening in some areas.
The heavy rain along the central coastal districts including Sydney Metro, Lower Hunter and Illawarra is expected to ease later today as the rain band contracts to the north and south.
The BoM has also issued warnings of damaging winds averaging 60km/h to 70 km/h, with peak gusts in excess of 90 km/h possible along the coastal fringe south of Seal Rocks from late this morning.
The SES – which has deployed about 2000 people – and other emergency services have been extremely busy over the past couple of days.
It has responded to 9000 jobs and carried out 870 flood rescues.
The BoM warned 10 million Australians were under a weather warning as two major systems collided, leaving Western Australia the only mainland state not affected.
“It may have been going for days but unfortunately this situation is far from over,” the BoM said.
Warnings for heavy rain, damaging winds and heavy surf cover an area similar in size to Alaska.
Meanwhile, the Australian Defence Force will send two search and rescue helicopters to flooded areas today after NSW requested backup.
“The search and rescue choppers will be able to work through night and day and supporting personnel will be made available to make this happen,” David Littleproud, the Minister for Emergency Management, said.