The NSW State Emergency Service (SES) has called in extra resources to the state's Mid North Coast ahead of predicted downpours in excess of 100 millimetres on Saturday.
The entire northern half of the NSW coast has been put on notice for heavy rain, gusty winds, flash flooding and large waves.
However, areas between Coffs Harbour and Port Macquarie are expected to bear the brunt of a rain band predicted to develop across the state.
"The biggest risk over the weekend is going to be a flash flooding story with an intense downpour," Coffs Harbour SES deputy unit commander Martin Wells said.
An initial flood watch has been issued for minor flooding on the Orara, Hastings, Bellinger and Kalang river catchments and residents in nearby low-lying areas have been told to be prepared for possible isolation if floodwaters rise.
"Because of the size of the low, it's quite unpredictable," NSW SES Northern Zone's Scott McLennan said.
A helicopter has been placed on standby in Coffs Harbour and a high-clearance vehicle has been brought from Lismore to assist in the event of any rescues.
Concern for Orara River
Mr McLennan advised residents around the Orara River catchment to be alert due to ongoing bridge repairs.
"Coutts Crossing are currently having their bridges replaced, so they've actually got a diversion that goes lower than the normal flood height for the bridge," he said.
"So, we're quite concerned for the communities of Nymboida, McPhersons Crossing and Coutts Crossing itself because the only road to Grafton, the diversion, is lower than what we anticipated."
Mr McLennan urged those residents to reconsider Father's Day travel plans due to the potential impacts on the roads.
The coastline is also expected to be lashed with rain and wind.
The Bureau of Meteorology (BOM) has issued a hazardous surf warning and a gale marine warning from the Hunter to the Byron coasts on Saturday.
BOM community engagement officer Morgan Pumpa said people needed to keep themselves informed about the conditions and any changes.
"The wettest day is expected to be Saturday and the day we highly recommend people monitor the radar and make sure they're checking that forecast as well as the warnings," he said.
Mr Wells urged communities to review flood plans and avoid driving or travelling through flood waters.
"You might think the water is only half a metre or a metre high ... but you have no idea what's happening underneath."
