Minor flood warnings have been issued for Bellingen and Coffs Harbour on the NSW mid-north coast after the area received more than 120mm of rain in 12 hours.

The Bureau of Meteorology (BoM) issued the warnings after heavy rain lashed the flood-prone area overnight, and with more rain expected throughout Friday.

The rain is expected to cause minor flooding of the Bellinger River and Coffs Creek, the BoM said.

However, NSW Flood Warning Centre manager Gordon McKay said the problem would be nowhere near as bad as it was earlier this year, when towns like Bellingen were isolated following torrential rains.

Mr McKay said falls of 120mm to 150mm had been recorded in parts of the mid-north coast, with similar falls likely in the northern rivers over the next 24 to 36 hours.

Rain was likely to ease around Coffs Harbour later on Friday as the wet weather moved north.

A flood watch, a step below a minor flood warning, has also been issued for the northern rivers area around Grafton and Lismore.

"The main action at the moment is on the mid-north coast, around Coffs Harbour, Bellingen and Nambucca," Mr McKay told AAP.

"We expect the rain to ease off on the mid-north coast and then intensify further north.

"But at this stage we're looking at minor to moderate flooding, not hundreds of millimetres to cause major flooding."

A minor flood warning has also been issued for Hungerford on the Paroo River, in the north west of NSW.