Emergency services are bracing for another wet day as rain continues to drench parts of NSW, with residents across Sydney, the Illawarra and the South Coast urged to prepare themselves.
The Bureau of Meteorology expects widespread rainfall to continue on the state's coast, after some stations in northern NSW recorded more than 300mm within 48 hours.
The BOM acting NSW state manager Jane Golding said rain was expected to intensify overnight and through Sunday.
A severe weather warning for very heavy rain, high winds, large waves and tides has been issued along the entire coast from the Northern Rivers region to the South Coast.
"Potentially we haven't seen anything like this since the late 1990s," Ms Golding said.
BOM senior forecaster Jordan Notara on Saturday afternoon said they could see 100 to 200mm falling over metropolitan Sydney and surrounds within the following 12 to 24 hours.
He warned that could cause "inundation on some places along the coast, minor to major flooding over some catchments and very strong winds along the coastline".
Mt Elliot (184mm), Toukley (159mm), Kangy Angy (140mm) and Wyong (125mm) received heavy falls from 9pm on Friday to 4am on Saturday.
Over 300mm was recorded at stations surrounding Byron Bay within the 48 hours to 9am Saturday.
The NSW SES has received more than 2600 calls for help since midnight on Wednesday and responded to at least 20 flood rescues, mostly involving motorists who drove into floodwaters.
On Saturday night they urged residents across Sydney, the Illawarra and the South Coast to prepare for heavy rain and potential flooding.
The BOM has issued minor flood warnings for a number of catchments including the Cooks River, Orara River and Tuggerah Lake, and a minor to moderate warning for the Hawkesbury and Nepean rivers.
The NSW SES said residents in rural areas should move stock and equipment to higher ground.
A video was posted online of a man driving his jetski past a McDonald's down a flooded street in Tuggerah on the Central Coast.
It drew swift condemnation from NSW Police minister David Elliott, who labelled the driver a "boofhead" and asked police to investigate.
BOM says the trough bringing persistent rain and windy conditions will continue extending into the southern coast on Sunday.
Damaging wind gusts exceeding 90km/h are possible along the coastal fringe between Ulladulla and Forster, and damaging surf conditions are forecast to develop on Saturday night or Sunday.
BOM also warned that the burned-out landscape and loss of vegetation on the fire-affected South Coast had left it vulnerable to landslips.
There were 38 fires still burning throughout the state on Saturday evening.
Australian Associated Press