Coffs Harbour is on track for its wettest year since records began in 1942.

So far the city has received 2,821 millimetres of rain.

Bureau of Meteorology climatologist, Agata Imielska, says the average rainfall is 1,683 millimetres.

She says the city only needs another 63 millimetres of rain to break the record.

"Going by what we expect to see in November and December, around 130 millimetres, we do expect that record to be broken by the end of the year," she said.

"It's a number of factors, for example having an upper level feature as well as a low pressure trough or an upper low or any of those things combined with a supply of moisture to Coffs Harbour can result in heavy falls in the area."

Ms Imielska says the excess rainfall has been caused by an unsteady synoptic situation as well as warmer than normal ocean temperatures.

"In the previous events we've had very warm temperatures, an easterly flow and a few other factors contributing to the falls that you've had," she said.

"So it's already the second highest rainfall total on record and going by what we expect to see in November and December around 130 millimetres, we do expect that record to be broken by the end of the year."

Bellingen has already had its wettest year on record, with a record 3,416 millimetres for the year so far.

The previous highest rainfall was 2,895 millimetres in 1921.