Surfers descended on popular local breaks across the Illawarra to take on waves of around three metres, while avoiding areas that were too exposed to the wind.

The BoM warning for damaging winds and dangerous surf extends from from Eden to Byron Bay and was forecast to impact the NSW coastline from Friday through to at least Sunday.

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Conditions are expected to be hazardous for coastal activities such as rock fishing, boating, surfing and swimming.

People should consider staying out of the water and avoid walking near surf-exposed areas. Rock fishers should avoid coastal rock platforms exposed to the ocean and seek a safe location that is sheltered from the surf.

Andrew Ugarte, NSW State Operations Manager at Surf Life Saving NSW said conditions on parts of the NSW coastline are already very dangerous.

"We urge members of the public to exercise extreme caution on the NSW coastline today and across the weekend and not to engage in risky coastal activities," Andrew Ugarte said.

"If people put themselves in danger in these extreme conditions, there's a real chance that lifesavers will not be able to save them, or at the very least, risk their own lives in doing so."

With swells up to four metres forecast in some locations and gale-force winds, there is a threat of coastal inundation, erosion and flooding in low-lying areas.

Surf Life Saving NSW will have Duty Officers and surf rescue assets on standby across the weekend.

The high winds and large surf conditions mean most beaches and rock platforms in particular will be treacherous this weekend.

"The forecast weather pattern will produce high winds, damaging surf with significant wave height and substantial rainfall in some areas. It will create extremely dangerous conditions for swimmers, surfers, rock fishers and boaters," Andrew Ugarte concluded.