The rain continues to play havoc with the regions roads, with police and SES called to attend a landslip at the Princes Highway in West Wollongong on Saturday afternoon.

Traffic going south outside The Illawarra Grammar School was down to one lane due to the incident.

Elsewhere, there has been a three vehicle crash on Macquarie Pass, with motorists advised to avoid the area.

Across the state, rain has eased slightly is expected to return with renewed intensity as the north of the state is warned to brace for severe weather.

Several days of heavy rain which saw some areas receive more rain in 24 hours than would be expected for the entire month of February is expected to be followed by a low pressure system developing in south east Queensland moving south.

Intense localised falls are expected on Sunday, with thunderstorms a factor as well.

An evacuation warning has been issued in the Northern Rivers for residents in low-lying areas of Maclean, where the Clarence River is expected to flood properties and cut off evacuation routes.

On Saturday, the Illawarra recorded the state's heaviest falls, with 63mm falling at Bellambi in the five hours up to 2pm on Saturday.

About 31mm fell in the same period at Cronulla, in Sydney's south, while Pillar Valley, east of Grafton in the Northern Rivers, received 34mm.

In February to date, 317mm has fallen at the Bellambi Point radar, which is more than double the long term monthly average.

The record monthly total, 399 mm, was received in February 2020, in the drought breaking rain that followed the bushfires.

The SES has warned people to stay off the roads unless necessary and not drive through floodwaters.

"It only takes 150mm of water to float the average car, and with flooding damaging most roads you don't know the condition under the water," the SES warned.

The SES received 689 requests for assistance around NSW since noon on Friday and conducted four flood rescues in that time.

with Australian Associated Press