While the rain is starting to ease across much of Sydney, flood risks remain with the deluge hitting saturated catchments and pushing several other dams beyond capacity.
Residents have been told to prepare to evacuate from low-lying areas along the Georges River at Chipping Norton in Sydney's west ahead of predicted flooding
And the flood threat has been heightened further south of Sydney with the surface trough, which has been generating heavy falls, moving south on Friday.
Warragamba dam began spilling over on Friday morning at a rate of about 150 gigalitres of water a day, while inflows were 270GL a day and rising, WaterNSW said in a statement.
It is the third consecutive month the dam has spilled.
The dam supplies 80 per cent of Sydney's drinking water and releasing water to reduce storage levels and mitigate flooding ahead of predicted rainfall is not permitted.
It came as the catchment received 87mm of rain in 48 hours.
Dams southwest of Sydney at Woronora, Nepean, Cataract, Cordeaux, Avon and Tallowa were all spilling on Friday morning as well, along with storage areas in the Blue Mountains.
A severe weather warning issued by the Bureau of Meteorology advised heavy rain will continue in the Illawarra region and the south coast of NSW on Friday afternoon, as rain eases around Sydney.
As much as 100mm could fall in six hours in some areas, while others have already copped a drenching, the bureau warned.
Prepare and plan your travel! 🚗— NSW SES (@NSWSES) Remember that with heavy rainfall you need to drive with extra caution. Roads on your journey may be closed due to flood water.🗺� With increased traffic due to the long weekend, it is important that you plan your trip using @LiveTrafficNSW pic.twitter.com/PEb1ENlGh9June 7, 2024
At Cringila in Wollongong's south, 214mm of rain fell in 24 hours to 9am on Friday, with 204mm at Port Kembla and 156mm at Wollongong.
The bureau's senior meteorologist Angus Hines said those areas were nearing double their monthly average earlier on Friday.
The rain should begin to ease on Friday afternoon, with sparse showers continuing along the south coast.
However, flood risks remain as the downpours ease.
"Any further wet weather in the next few hours and for the rest of the day, will be falling onto saturated land ... adding to or extending potential flooding impacts," Mr Hines said.
The Nepean River may reach 10 metres by noon at Menangle, southwest of Sydney and downstream from Warragamba, with people there advised to monitor the conditions and alerts by the State Emergency Service.
Emergency crews have conducted dozens of rescues, with more flooding likely. (HANDOUT/NSW RURAL FIRE SERVICE)
Moderate flooding is likely along the Colo, Hawkesbury and Nepean rivers in Sydney's west and the Georges and Woronora rivers in the city's south.
"The rivers have seen a rapid response to the amount of rainfall in the past 24 to 36 hours," Mr Hines said.
"As this rain that's fallen over the last day or two works its way down through the river network, there are other waterways and rivers that could rise and exceed their flood thresholds."
The SES conducted 49 flood rescues, responding to 447 incidents across the state in the 24 hours to 5am on Friday.
The majority were in the south eastern region hit by the heaviest rain, with 291.
Buses are replacing trains between Wollongong and Port Kembla due to flooding.
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