The NSW SES has urged residents and visitors to take action now to prepare for possible flooding, particularly for residents of Liverpool, St Aubins, Wingen, Kingdon, Aberdeen, Mount, Susan and Parker streets.

Storm and flood impacts may interrupt essential services such as electricity, phones, internet, water and sewerage, the SES has advised in its latest alert.

Flooding and rainfall: SES on watch in Lower Hunter as rainfall moves downstream

"People in these areas need to closely monitor weather and road closures and make informed decisions early based on individual circumstances," a spokesperson said.

Residents have been advised to monitor the situation and to evacuate if and when they are told to do so.

"Once floodwater begins inundating the area, road access may be cut," the spokesperson said, "If you remain in the area after this time, you may become trapped and it may be too dangerous for NSW SES to rescue you."

Elsewhere in the region, significant water level rise along the Paterson River at Gostwyck is likely to result in minor flooding early Friday evening, while the Williams River at Tilligra peaked Friday afternoon, the SES has advised.

The main flood peak along the Williams River is approaching Dungog, where river levels are likely to peak Friday night.

The Paterson River at Gostwyck Bridge is likely to reach around 9.20 metres.

Residents at Bendolba and Bandon Grove may be isolated, once the river exceeds 4.9 meters at the Dungog gauge, residents should prepare now for possible isolation. Residents have been advised to monitor the situation and plan for possible road closures and inundation in low-lying areas.

Moderate rainfall across the upper Hunter River catchment on Thursday and Friday has already caused major flooding at Kingdon Ponds, with water levels peaking on Friday afternoon.

Moderate flooding is likely along the Upper Hunter River at Muswellbrook Friday night, NSW SES incident controller Joanna Jones advised.

Minor flooding is likely at Aberdeen Friday evening and at Denman overnight Friday and into Saturday.

"Major flooding is occurring at Kingdon Ponds. Moderate flooding is likely along he Upper Hunter River at Muswellbrook. Minor flooding is likely at Aberdeen and Denman," Ms Jones said in a statement Friday afternoon.

"The Scone at Kingdon Ponds peaked at 3.88 metres around 3.10pm Friday and is currently at 3.79 metres and falling, with major flooding.

"The Hunter River at Aberdeen is likely to reach around 7.40 metres Friday night, with minor flooding.

"The Hunter River at Muswellbrook is likely to exceed the minor flood level 7.20 metres, around 6pm Friday. The river level is likely to reach around 8.20 metres Friday night, with moderate flooding.

"The Hunter River at Denman is likely to reach the minor flood level, 6.50 metres, overnight Friday into Saturday."

Steady showers are expected to settle over the Upper Hunter for the coming week, with tops of 30 degrees on Thursday at Scone and Muswellbrook.

Local communities need to closely monitor the situation and plan ahead around possible road closures and inundation of low lying areas.

Residents at Bendolba and Bandon Grove may be isolated, once the river exceeds 4.9 meters at the Dungog gauge, residents should prepare now for possible isolation.

For emergency help in floods and storms, call the NSW State Emergency Service on 132 500. In life threatening situations call triple zero (000) immediately.

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