NSW Premier Mike Baird has toured flood-ravaged northern NSW, seeing firsthand the devastation two days of heavy rains and wild winds have brought.

Mr Baird flew over the flood affected areas earlier today as State Emergency Service volunteers try to reach the remaining residents, including elderly people in need of medication, isolated by flood waters around the Hunter town of Maitland.

The area has already been struck by tragedy during the recent storms, with an 86-year-old local woman who died after her car was washed off the road.

Supplied are prepared for the stranded residents in Gillieston Heights. (9NEWS) (9NEWS)

A home in Milperra remains partly underwater after the Georges River broke its banks. (Supplied) (Supplied)

Police today had just one boat to supply the town, but it will be joined early this afternoon by two more boats sent from Singleton.

Medicine, food and water were highest on the list of priorities to be sent over, police said.

There is an aged care facility in the town, with a number of residents in need of medication.

Gillieston Heights has a population of about 1300, but police are unaware how many were isolated in the town.

A police spokesman said he expected it to be "at least a couple of days" before floodwaters receded enough to make the roads passable again.

NSW Premier Mike Baird has arrived in the Hunter to visit flood-hit areas.

The Georges River has broken its banks, flooding suburbs in Sydney's southwest. (9NEWS) (9NEWS)

Meanwhile, residents evacuated from the flood-ravaged Sydney suburb of Milperra will be allowed to return to their homes, despite the area still looking like an inland lake.

Sixty homes were evacuated yesterday after the Georges River broke its banks, leaving homes and vehicles underwater.

The SES was urging caution to returning residents, with some roads still underwater.

"It is now safe to return, however there is limited access to Newbridge Road East Bound near the Georges River for the next 3-4 hours whilst clean-up operations are undertaken," the SES said in a statement.

The SES has issued an evacuation order for 200 homes along the river. (9NEWS) (9NEWS)

Residents in storm-battered NSW towns have been warned to watch out for more flooding, as the heavy rain and gale-force winds slowly begin to ease.

The Bureau of Meteorology says the worst of wild weather is over, but has warned that flood peaks will still come today despite less rainfall across the state's east coast.

Send your storm photos and videos to contact@9news.com.au - but remember to stay safe.

On the Central Coast, residents have been encouraged to prepare with sandbags after Tuggerah Lake peaked near 1.45m this morning.

Minor flooding is expected to continue at the lake throughout today and tomorrow.

North west of Sydney, about 2000 people remain cut off by flooding around the Colo River.

A four-month-old baby was evacuated during a flood rescue operation near Maitland. (9NEWS) (9NEWS)

There are still 155,000 NSW homes without power, after thousands of wires were brought down by the storm.

A total of 132 flood rescues had been made since the wild weather began.

Emergency crews have saved a man washed off his bicycle while riding along a flooding weir in Penrith as authorities beg people not to ride, drive or walk through flood waters.

The 18-year-old man was riding with two friends, aged 17 and 21, when he was swept off his bike.

He was able to grab a nearby tree and held on until emergency services arrived to bring him to shore.

There were four fatalities directly as a result of the storms, and four other people died in traffic accidents on wet roads.

The SES said the slow-moving low pressure system off the Hunter coast would weaken on Thursday and "lead to improved weather conditions over eastern New South Wales"

Key updates:

• The state death toll stands at four;

• Commuters have been advised to avoid all non-essential travel in affected areas and to not enter flood waters;

• The SES has received 12,776 requests for assistance and performed 132 rescues;

• Up to 155,000 homes and businesses are still without power and crews are responding to reports of more than 6000 hazards;

IN PICTURES: Havoc wreaked by the NSW storm View Gallery