Beachgoers have been warned hefty waves are set to crash into Sydney beaches as a cyclone swell triggers powerful surf conditions along the NSW coast.

Surfers at North Narrabeen on Friday take advantage of the start of several days of massive swells along the NSW and Queensland coasts. Credit:Nick Moir

The Bureau of Meteorology issued a hazardous surf warning for NSW, warning of dangerous conditions for swimmers, boaters and rock fishermen on Saturday.

Senior forecaster Neale Fraser said tropical Cyclone Gita was bearing down on the New Caledonia coast and would whip up the swell as it continued to head west.