Dangerous surf along northern NSW coast

Surf Life Saving NSW has warned "extremely challenging" surf conditions are expected along NSW's northern coast over the weekend.

Dangerous surf conditions are forecast for northern NSW as Cyclone Oma sits off Queensland's coast. (AAP)

Beachgoers in northern NSW have been warned of dangerous surf and wind conditions as a cyclone tracks off the Queensland coast.

The Bureau of Meteorology on Friday warned Cyclone Oma, which is expected to remain offshore, is causing high winds, abnormally high tides and damaging surf along the state's northern coast.

A severe weather warning has been issued from Tweed Heads to Coffs Harbour while a hazardous surf warning is in place for the coastline between the Hunter and Tweed Heads over the weekend.

Beaches from Tweed Heads to Port Macquarie have been closed and are expected to remain closed until early next week.

Surf Life Saving NSW chief operating officer Phil Ayres urged beachgoers to remember if the flags are down, it's not safe to swim.

He said the conditions are "extremely challenging" and urged surfers and swimmers to not to overestimate their ability and underestimate the power of the ocean.

Rock fishers have also been urged to move to less exposed areas and to wear flotation devices.