Talk about a wall of water.
"Surf and swell conditions are expected to be hazardous for coastal activities such as rock fishing, boating and swimming," the agency said.
Video released by the weather service showed the constant action as numerous large swells battered the coast.
Waves peaked at a height of 38 feet off Sydney on Tuesday night.
Video posted to Twitter by Natali Pearson showed an ocean pool at Maroubra in Sydney’s east being swallowed by frequent large waves.
The conditions may not have been suitable for swimming, but surfers took advantage of the wild waves.
Many could be seen in photos and videos out in the water, with some falling and wiping out. No injuries or deaths have been reported, however.
One close call did happen at Avoca Beach in New South Wales, when a “freak wave” sent people running.
According to officials, the Central Coast Council assessed the area as there was damage to the foreshore and car park.
"There is still a hazardous surf warning for much of the NSW Coast," the fire brigade said.
The storm system that churned up the wild waves is known as an “east coast low” by the weather bureau, which frequently occurs during autumn and winter and is one of the more dangerous weather events to affect Australia's East Coast.