The Bureau of Meteorology has issued another flood watch for the Bellinger and Nambucca Rivers, saying the rainfall has the potential to cause minor to moderate flooding from late Thursday into the weekend.

A coastal trough deepening near the northern New South Wales coast this morning will gradually extend south on Friday generating unsettled weather and heavy rain.

Kevin Doye who runs the website bellingenweather.org said on his blog this morning, "Saturated ground, showers increasing, heavy falls likely - and a surface trough to further increase rain totals ... lots of weather to talk about."

The forecast indicates high likelihood of heavy rain, with about 60mm tomorrow and Friday, up to 100mm on Saturday and up to 50mm on Sunday.

Adding up the numbers above, that's a potential total of between 180mm and 280mm over the next four days.

That's coming on top of the 835mm that has fallen so far this year on the Coffs Coast.

The heavy rainfall is predicted to extend right across the Mid North Coast.

Locations which may be affected include Coffs Harbour, Port Macquarie, Taree, Woolgoolga, Sawtell and Dorrigo.