The warning also covers a developing southerly swell of four to five metres from Monday afternoon.

BOM forecaster Jiwon Park said the expected extra large south swell combined with very strong winds means most beaches and rock platforms will be extremely treacherous this week.

Surf Life Saving NSW CEO Steven Pearce urges the public to take extreme caution if they are visiting the coast.

"It's crucial for anyone visiting the coast to consider the risks associated with these conditions before putting themselves, their family and our lifeguards in danger," Mr Pearce said.

SLSNSW recommends the public visit beachsafe.org.au or download the Beachsafe App, to find current beach conditions across the state before heading to the beach.

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.

Boaters planning to cross shallow water and ocean bars should consider changing or delaying their voyage while boaters already on the water should carry the appropriate safety equipment and wear a lifejacket.

Boaters should remember to log on with their local Marine Rescue radio base, via VHF Radio or the Marine Rescue APP, and consider their safety management plan.

Weatherzone meteorologist Graeme Brittain said weather conditions will be fairly unsettled on Tuesday and Wednesday along the eastern seaboard, and particularly Port Macquarie.

"We have a developing low pressure system in the Tasman Sea that is going to send very gusty winds and heavy surf conditions to the Mid-North Coast, and the remainder of the eastern seaboard," he said.

"There is a damaging wind warning and damaging surf warning in place for the area.

"We are forecasting winds gusting to 90 kilometres per hour on exposed coastal parts," he said.

"Winds look to be at their worst on Tuesday afternoon and into the early evening."

Mr Brittain said winds - from the west, south west - will likely be noticeably gusty for much of Tuesday and into Wednesday.

Despite the windy conditions, Port Macquarie appears likely to escape any major rainfall with "a few millimetres only expected".

The meteorologist said any rainfall would be mainly coastal and will not extend too far inland.

"This weather pattern will be a classic case of feeling several degrees colder than the actual temperature," Mr Brittain said.

"Tuesday and Wednesday's maximum temperatures will be 17 and 18 degrees but it will certainly feel much cooler.

"Tuesday morning's minimum will be four degrees but with the prevailing winds will be feel closer to zero degrees," he said.

The weather should return to somewhere closer to the long term average with the maximum temperature of 21 degrees forecast for Thursday through to the end of the week.

The minimum temperatures will be between six and nine degrees.

Mr Brittain said the average maximum temperature for Port Macquarie through May was 23 degrees, which is about 1.5 degrees above the long term average.

The minimum temperature averaged 8.6 degrees, about 1.8 degrees below the long term average.

In terms of rainfall for May, Port Macquarie recorded just 25.6mm was recorded which is just over 20 per cent of the long term average.

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