More than 150 NSW schools have been closed as torrential downpours prompt evacuations around Sydney's south and southwest.
Residents have been ordered to evacuate houses and caravan parks after forecasters predicted historic flooding for parts of the state.
Evacuation orders were issued early on Friday for people in Cornwallis and the eastern part of Richmond lowlands as well as low-lying parts of Cattai, Pitt Town and Agnes Banks.
Residents in Camden and Chipping Norton in Sydney's southwest and Woronora, Bonnet Bay and Gronos Point were earlier ordered to evacuate as floodwaters began to rise on Thursday.
People were also warned to prepare for evacuation in parts of Ebenezer, Emu Plains, Mulgoa, Sackville North, Pitt Town Bottoms, Camden, Elderslie, Wallacia Weir and North Richmond for fear of being trapped without power and water.
Premier Dominic Perrottet said close to 2400 people were subject to 23 evacuation orders on Friday morning, with more than 17,000 being warned to prepare for evacuations.
He advised them to keep heeding the warnings.
Emergency Services Minister Steph Cooke said the state is experiencing flood fatigue but people need to keep following the advice of emergency services.
"It will stop raining, it will get better," Ms Cooke said.
"We just need to keep (getting) through this one day at a time."
The Bureau of Meteorology's Jane Golding said the rain is easing on Friday after downpours on Thursday.
"We do have flood warnings current though, so although the rain is easing ... we do have major flood warnings for some sites," she said.
"The rivers will be moving quickly (and) there's a lot of debris flowing around."
The SES received close to 1200 requests for assistance and conducted 35 rescues in the past 24 hours.
"Across a population base the size that we had under warning areas, 35 is actually quite a low number and we are really grateful for the community for listening," NSW SES acting commissioner Daniel Austin said.
More than 1200 SES volunteers have been on the ground as catchments react quickly to heavy rain causing flash flooding.
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The NSW education department has listed 154 schools, predominantly around Greater Sydney, the Illawarra and Shoalhaven regions that are not operating due to adverse weather conditions on Friday morning.
Major flood warnings are in place for rivers in the the Hawkesbury-Nepean Valley and the NSW Central and South Coast.
Water is also spilling over Warragamba Dam, which was at capacity when the downpour started.
A major flood peak above levels seen during the April 1988 floods passed through Menangle on Thursday afternoon, where the Nepean River reached 16.83 metres on Thursday afternoon before falling back to 11.75m by 7am on Friday.
Further downstream, the river exceeded last month's height at Camden Weir, reaching 12.21m about 10pm on Thursday before falling back to 11.03m by Friday morning.
Wallacia is expected to experience flooding at levels higher than last month when the Upper Nepean River peaks on Friday morning.
There is also major flooding at North Richmond on the Hawkesbury River, although the Bureau of Meteorology believes the rises will not be as severe as last month's flooding.
Australian Associated Press
