Massive swells and king tides combine to batter parts of Sydney's coast, causing damage at Bondi, Cronulla and Bronte Beach

Huge swells, a massive king tide and storm surges have battered some of Sydney's beaches including Bondi in the city's east and Cronulla in the south overnight.

Homes have also been impacted with residents living on Botany Bay in Sydney's south forced to evacuate around midnight last night as powerful surf and the king tide inundated homes.

At Sydney's Bondi Beach, the huge waves have damaged the Icebergs surf club at the beach's southern end.

CCTV footage at the club's gym entrance shows waves bursting through glass doors just after 11pm yesterday.

Swells reached 5.5 metres at Bondi last night, smashing glass and breaking a railing post from its foundation.

The club cafe, pool and gym were closed on Wednesday morning.

A large water storage tank also washed up on Bondi Beach overnight.

The surging surf also caused damage at Bronte Beach, knocking over two brick walls and scattering debris in the park.

The tide of almost 2 metres combined with a large, powerful surf and a storm surge to inundate homes around Caruthers Drive at Dolls Point.

Long-term Dolls Point resident Maree McCaskill said the water came in waist height and belted the fences.

"I've never seen the waves nearly as high," she said.

"The water was surging through my place going straight into the backyard and the person behind me is lower down so it's gone straight through their house.

Andrew Edmunds from the State Emergency Service said crews had to sandbag several properties, as waves several metres high crashed over the sea wall and flooded streets.

"Several properties were evacuated by Fire and Rescue NSW due to that saltwater ingress and damage. Crews from the Bayside unit did some sandbag properties as well," Mr Edmunds said.

Parts of Cronulla beach blocked off 

Sutherland Council lifeguard duty officer Steve Winner said Cronulla Beach had been badly impacted, with both the beach and esplanade damaged, including parts of the pavement.

"Last night there were waves over 4 metres. There are exposed electrical wires and pipes and waves still coming up," Mr Winner said.

Mr Winner said the beach had already been battered a few weeks ago from ex-tropical cyclone Alfred generated swells.

"So we have had to block all of that off due to safety and even Cronulla Beach the erosion is quite significant once again," he said.

A local resident Geoff told 702 ABC Radio Sydney he walks on Cronulla Beach's esplanade every morning.

He said the huge swell and king tides overnight caused some major problems.

Sandbags help in Wollongong, Coffs Coast erosion

Residents across the Coffs Coast have been waking up to the damage caused by king tides and dangerous surf conditions.

Sawtell resident Jeff Holmes said he was shocked by the extent of coastal erosion at his local break today.

"I've been here for 35 years, that's probably one of the steepest cuts I've ever seen on Sawtell main beach," Mr Holmes said.

Residents resulted in using a ladder to brave the 4-metre drop to the shoreline, before the beach was closed by council.

Coastal erosion specialist Stephan Soule from the National Marine Science Centre said the damage would be long-lasting.

"It's going to take a while, especially with the amount of sand that we've lost," he said.

"It could be even longer [than six months]."

Powerful surf caused land along Wamberal Beach in the Central Coast, where several beachfront homes sit, to slip.

Nearby residents have been fighting for a seawall since severe storms caused significant damage in July 2020.

"It's quite scary out there at the moment … there has been substantial erosion and concrete has fallen onto the beach," resident Chris Rogers said on Wednesday morning.

The Austinmer Beach car park in the Illawarra went completely underwater, while at North Wollongong, a new extension to the surf club is surviving due to sandbags, with the foundations now clearly exposed.

The Illawarra bore the brunt of the swell located directly west of the deep low pressure system producing 5 metre swells on Tuesday afternoon and evening.

In Kiama, the waves were so large on Tuesday the famous blowhole onlookers were soaked.

Kiama Surf Lifesaving Club president Phil Perry said water at one stage flooded the grass around the club and infiltrated the downstairs area and gym.

"It's not normal to see the water up that high," he said.

Port Kembla Lifeguards rescued two teenage boys swept out to sea on Fisherman's Beach in Port Kembla on Tuesday afternoon.

Emergency services were alerted to the rescue about midday and assisted lifeguards in rescuing the pair as they were swept 250 metres out to sea.

There is also a flood watch current for parts of the Mid North Coast, Northern Rivers and North West slopes where rainfalls of between 40 millimetres and 100mm could lead to flash flooding and river rises.

There is a warning for hazardous and damaging surf with the potential to cause coastal erosion and damage from the NSW Illawarra to the Hunter coasts.