Between 9am and 5pm Saturday, most of Newcastle's suburban areas received less than 25mm of rain with even less around Maitland and Cessnock.

Falls were slightly greater in southern Lake Macquarie and on the Central Coast, where 40mm was recorded at Toukley.

Similar rainfall was recorded along the Mid North Coast on Saturday, but those areas had experienced a huge downpour in the 24 hours prior.

Majority of the Mid North Coast received well over 100mm in that period with multiple sites recording more than 300mm and one in excess of 400mm.

The Pacific Highway remains closed in both directions from Coopernook To Glenthorne between George Gibson Drive and Manning River Drive/Old Bar Road.

The Paterson River at Gostwyck Bridge was peaking at 13.55 metres about 4pm on Saturday with major flooding being experienced.

The Williams River at Mill Dam Falls was peaking at 9.30 metres.

Low lying rural properties and roads were expected to be affected at both locations.

The State Emergency Service was also warning of minor flooding along the Wollombi Brook on Saturday evening, particularly at Bulga and Broke.

Rising water in the Hunter River was also expected to cause minor issues at Maitland and Raymond Terrace.

Less than 50mm of rain is predicted along the Hunter's coastal areas on Sunday. Even less is set to fall in the Hunter Valley.

The SES had 1000 requests for assistance from across the Mid North Coast and the Hunter.

"Over 500 of those were flood rescue," NSW SES media officer David Rankin said on Saturday evening.

"It's been an unprecedented number of flood rescues that we've experienced in a very short period of time.

"We've had a few in the Hunter but the vast majority have been up around Wingham, Old Bar, Port Macquarie and Kempsey.

"The Hunter has been spared the worst of it."

A major flood warning is in place for the Williams and Paterson rivers after heavy rain over the Barrington Tops and much of the Hunter on Friday night.

The Williams River at Dungog was expected to exceed the major flood level at 10am and peak above 9.0 metres on Saturday afternoon.

The NSW SES is advising residents in low lying areas of Dungog that they may need to evacuate due to rising waters, however a flood evacuation order is yet to be issued.

These areas include:

The Paterson River at Gostwyck Bridge was predicted to exceed the major flood level (12.20 m) at 9am.

It may peak at 14.50 metres in the afternoon and further rises are possible, the Bureau of Meteorology has warned.

Low lying properties near the Myall River at Bulahdelah were told to evacuate overnight. Parts of Gloucester were also under water.

The Hunter deluge is expected to intensify today with parts of the Mid North Coast having received more than 350mm of rain in the 24 hours to 9am Saturday.

A house was swept down the Manning River earlier this morning.

Careys Peak in the Barrington Tops recorded 179mm, Bulahdelah 154mm, Nelson Bay 105mm and Gostwyck Bridge near Paterson 100mm.

Much of the Lower Hunter recorded at least 50mm.

The region is subject to multiple severe weather warnings, including for heavy rainfall, damaging winds and surf.

A Bureau of Meteorology update on Saturday warned of very heavy rainfall which would likely lead to flashing flooding that presented "a serious risk".

Parts of the Mid North Coast were warned of potentially "life threatening" flash flooding.

The heaviest falls in the Hunter are expected until late afternoon. Between 50 and 100mm is expected across the Lower Hunter.

"A low pressure trough lying along the New South Wales coast is generating widespread and persistent rain in many eastern districts, along with windy conditions," the BOM said in a statement.

"This trough, in conjunction with a strong high pressure system to the south, is also bringing windy weather to higher parts of the southern ranges.

"Most areas will see the heaviest rain during the next 24 hours, however some places are forecast to experience periods of heavy rain through to Monday or Tuesday."

READ MORE: Flooding fears: Rivers rise as more rain in store

Wind gusts in excess of 90 km/h are expected along the coast.

The BOM said the "vigorous winds" would likely result in huge surf with wave heights up to five metres in the surf zone.

The weather has closed multiple roads and parts of the state's public transport system.

No trains are running on the Hunter Line due to flooding.

Likewise between Newcastle and Fassifern on the Central Coast & Newcastle Line.

Buses are replacing passenger services on both lines.

Newcastle Light Rail services are also suspended. Busways has advised its Route 151 - Newcastle to Taree via Forster, Hawks Nest & Tea Gardens service departing Newcastle at 4:18pm is cancelled.

The Pacific Highway is closed in both directions from Coopernook To Glenthorne between Harrington Road and Manning River Drive/Old Bar Road.

It is also closed at Moorland between Hannam Vale Road and Jericho Road.

Maitland Vale Road is closed at Maitland between Melville Ford Road and Luskintyre Road.

Ausgrid has advised power is currently out to customers in Caves Beach, Swansea and Swansea Heads.

It is also understood to have been lost overnight in Cessnock, Lovedale and Neath.

This story will be updated throughout Saturday.

In life threatening emergencies, call 000 (triple zero) immediately. If you require rescue, assistance to evacuate or other emergency help, ring NSW SES on 132 500.

For more emergency information, advice, and access to the latest river heights and rainfall observations and forecasts: