An average of 120 millimetres of rain has fallen across the Manning valley since 9am Friday, the Bureau of Meteorology reports.
Heavy widespread rain is forecast over the catchment for the next 12 hours.
The following preliminary river height predictions are based on the expected rain.
At this stage it is not possible to predict the flood peaks because of uncertainty over how much more rain will fall.
Preliminary river height predictions:
Gloucester - Reach Minor flood level [4.0 m] this afternoon.
Mt George - Exceed Minor flood level early this afternoon
Wingham - Exceed 6.0 m this afternoon with Minor flooding.
Taree - Exceed Minor flood level this afternoon.
Harrington - Reach Minor flood level tonight.
FloodSafe advice is available at www.ses.nsw.gov.au
For emergency assistance call the SES on telephone number 132 500. For life threatening emergencies, call 000 immediately.
* For more on road issues in the Manning, click here