Two Black Hawk helicopters are helping flood-relief efforts in northern NSW, while residents and emergency services are sandbagging properties in flood-ravaged Coffs Harbour.

The flood situation in the region is worsening with heavy rain again pummelling the region.

State Emergency Services (SES) spokesman David Webber said crews were focused on Coffs Harbour on Australia Day.

"We've had 111 requests for assistance, particularly for sandbagging today," Mr Webber told AAP.

"About three-quarters of those jobs have been completed.