Floodwaters reach peak levels on the NSW south coast

Hundreds of people will spend another night out of their homes due to floodwaters on parts of the New South Wales south coast.

Earlier today the SES put evacuation orders in place for parts of Sussex Inlet and St Georges Basin, where floodwaters peaked around 5pm.

With the waters now expected to slowly recede, residents are eagerly waiting to get back home to see what damage has been done to their property.

For now though, locals are being told to stay out of the water for health reasons, as the flooding has caused some parts of the region's sewer system to fail.

People who have lived in the area for decades told 7 News that they had never seen flooding have such a devastating impact on the region.

"It was a shock when I got home, I didn't expect to see a water level this high," flood victim Bill Carruthers said.

"I've had water in the backyard before, but it's in the backyard, through the house and out the front yard today," added another flood victim.

Overnight 300 people were ordered to evacuate their homes in the two regions, with some taking shelter in evacuation centres set up at Sussex Inlet and Sanctuary Point.

The SES also doorknocked around 40 properties at Shoalhaven Heads this morning, due to moderate flooding which may be impacted by further rainfall.

Around 60 school students were evacuated from the Berry Sport and Recreational Centre and Wollongong University's Shoalhaven campus and Terara Primary School both closed their gates on Wednesday morning.

The Bureau of Meteorology has also issued a minor flood warning for the Nepean and Hawkesbury rivers due to heavy rainfall over the last two days.

Warragamba Dam is expected to start spilling overnight. At this stage minor flood peaks downstream of Warragamba Dam are expected to be similar to the March 2012 event.

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The SES are urging any residents trapped by flooding to take refuge in the highest available place and to call triple zero.

Under no circumstances are people to drive, walk or ride through flooded areas.

Meanwhile the SES has given the all clear for residents living downstream from the Jerrara Dam, west of Kiama, to return home.

Residents living in the lower areas of Mt Brandon Road, Jerrara Road and Jamberoo Road were evacuated on Tuesday morning following concerns the dam's wall showed signs of failing.

Engineers from Kiama Council, along with the NSW SES, have assessed the dam and issued an "all clear" on Wednesday morning.

The SES have worked tirelessly to attend to the 1500 calls for help since the storm first hit central NSW and Sydney on Monday, before sweeping south to the Illawarra and south coast regions.

The Bureau of Meteorology is warning of very heavy surf conditions and coastal erosion for parts of the Illawarra and South Coast districts.

The SES is concerned people do not understand the grave threats of entering flood water.

"We do not want people entering flood water - there are just so many different dangers to people," the SES spokeswoman said.

Moderate rain falls are still persisting in the lower Shoalhaven Valley, with showers expected to subside this afternoon, according to the latest BoM report.