A man has died and more than 160 people have required rescuing as a deluge across eastern NSW caused landslips, flash flooding and rapid river rises.
Suburbs on Sydney's fringes are facing the threat of significant flooding after copping more than a month's rain overnight while a major landslip in the Blue Mountains has cut off a community.
A home was washed into a street in Mount Keira in Wollongong which was smashed with between 200mm and 250mm of rain in 24 hours.
The storm threat was reduced late on Saturday afternoon with a severe weather warning cancelled over the far south coast.
Premier Chris Minns earlier called for caution amid expected days-long riverine flooding.
"It's important to note that flood levels in some of the rivers, particularly in western Sydney, are continuing to rise," he told reporters on Saturday.
The intense rainfall and flash flooding appeared to have claimed a life after a body was spotted in water near a Penrith reserve about 7.30am Saturday.
Formal identification of the man and his cause of death are yet to be determined.
Mr Minns thanked 4000 SES volunteers who endured wet conditions and "saved people's lives" on Friday and Saturday, conducting some 168 flood rescues statewide including 75 in the metro area.
A man was rescued from floodwaters while clinging to a submerged excavator in Erskine Park, west of Sydney, while a car was swept into a stormwater drain in Padstow and a train became stuck in Bardwell Park.
Fire crews joined SES crews to save a woman stranded in her car in fast-moving, knee-deep water in Dapto, south of Wollongong.
The SES said it responded to 3135 calls in 24 hours.
"Volunteers did an incredible job responding to hundreds of flood rescues, mostly for drivers caught in flash flooding,” Assistant Commissioner Dean Storey said.
"This demonstrates the skill, professionalism and dedication of our volunteers."
Eleven urgent evacuation warnings remained active late on Saturday afternoon primarily for communities along the Hawkesbury-Nepean in Sydney's northwest.
Parts of Sackville, Ebenezer and Leets Vale were told to leave by 5pm while the North Richmond area was subject to evacuation orders after moderate flooding closed key bridges.
Some areas in the west copped more than 200mm to 9am Saturday with Penrith recording five times its April average across 48 hours.
Residents on Sydney's northern beaches were told to return home with caution after dangerous and rising waters flooded fields and roads around Narrabeen Lagoon.
A similar message was issued to those in Liverpool and surrounds hours after the Georges burst its banks.
Numerous national parks were closed, including the urban forest Lane Cove National Park.
The slow-moving system moved over the far south coast on Saturday afternoon, bringing widespread heavy rain and thunderstorms south of Batemans Bay.
The coastal town earlier recorded a wave of 8.6 metres amid warnings along the coast for dangerous surf.
The inland low would move south into the Tasman Sea on Saturday night but an associated trough would continue to impact northern NSW and southern Queensland overnight, the bureau said.
Landslips remain a concern including in the Blue Mountains where one on a primary access road cut off a community and had authorities scrambling to arrange food drops.
"It's the only access in and out of the valley," Mike Davis, the owner of nearby vineyard Megalong Creek Estate, told AAP.
"A lot of people are down here camping or in Airbnbs at the moment so they need to do something fast."
Warragamba Dam also spilled just before 6am on Saturday after 100mm of rain fell over the catchment in less than six hours.
About 40,000 homes and businesses lost power in the past 24 hours with fallen trees and powerlines further interrupting supply, Ausgrid said in a statement.
