A developing coastal trough will see rain start to fall tonight, initially heaviest in Kempsey and then moving north.

Weatherzone is predicting rainfall of 40-80mm for Bellingen on four consecutive days, Friday to Monday.

Worst case, this would be a staggering 320mm, a fifth of our normal annual total.

The BOM's beta forecast service for Bellingen is suggesting 50-80mm on Friday, 80-150mm on Saturday, a mere 10-35mm on Sunday and 60-100mm on Monday.

The chance of any rain on these days is put at 90-95 per cent.

Figures for Dorrigo are looking less extreme: 20-60mm on Friday, 15-40mm on Saturday, 10-35mm on Sunday and 50-100mm on Monday.

The State Emergency Service (SES) said storms are also possible along the coast and are advising residents to ensure properties are storm-ready.

The BoM says a high-pressure system over the Bight is extending a ridge across New South Wales but will weaken by Thursday allowing a trough to move through southern and western parts of the state.

Meanwhile, over at belllingenweather.org, Kev suggested on his blog yesterday: "Now could be a good time to consider assets at rivers and outdoors, consider how much food you have in your larder if you live in an area vulnerable to being cut off with heavy rains, and keep an eye on the models and BoM warnings."

Update Thursday 1.45pm: The BOM has issued a "minor to moderate" flood warning for the Bellinger and Kalang Rivers starting on Saturday.