The Joint Australian Tsunami Warning Centre (JATWC) issued the below at 3.53pm Sunday, January 16, saying its threat assessment was unchanged.

"For the marine environment over all coastal areas there is the possibility of dangerous rips, waves and strong ocean current, and some localised overflow on to the immediate foreshore.

While evacuations are not necessary for Marine Threat areas, people in these areas are advised to get out of the water and move away from the immediate water's edge.

Throughout Saturday night Tsunami wave action continued to be observed along parts of the East Coast. The Tsunami Warning for the marine environment is expected to stay in place Sunday until there has been a clear period of several hours where observations show the threat level has eased.

Warnings will be updated each hour for the duration of the event.

In a timelapse video posted to Twitter (above), ANU Professor Louis Moresi showed how the tsunami reversed the tide at the Bega River mouth at Mogareeka.

For the latest and further information on tsunami warnings, call 1300 TSUNAMI (1300 878 626) or visit www.bom.gov.au/tsunami

For urgent emergency assistance call Triple-Zero (000)

For emergency service advice or general assistance call the NSW State Emergency Service on 132 500.

NSW State Emergency Service (NSW SES) and Surf Life Saving NSW are urging the public to continue staying clear of beaches due to ongoing hazardous surf conditions.

Following the volcanic eruption in the Tongan Islands Saturday night, the Bureau of Meteorology issued a Marine Tsunami Warning for the NSW Coast. This warning was to highlight the potential for dangerous rips and waves, strong ocean currents and some localised overflow onto the foreshore.

Surf Life Saving NSW has observed these conditions throughout the day, and as a result, beaches will remain closed. Beaches will then be assessed tomorrow (Monday, January 17) by local councils and Surf Life Saving NSW to determine if they will be safe to open again.

NSW SES Assistant Commissioner Sean Kearns said the public must stay clear of the water.

"The surf conditions will likely remain hazardous well into tomorrow," Mr Kearns said.

"There is also a chance we could experience severe weather this afternoon, which could only add further dangers," he said.

Surf Life Saving NSW Director of Lifesaving, Joel Wiseman agreed, saying it was important the public was aware of the dangers the conditions posed.

"Surf Life Saving NSW's position is always for the benefit and safety of the public, and while we have remained proactive and operational despite flags being down during the course of the Marine Tsunami Warning, we hope that potential beachgoers understand the risks associated with the hazardous surf conditions," he said.

"As an organisation, we are rescue ready and have Support Operations actively working across the state to ensure optimal safety on our coastlines, but we still encourage anyone planning to head to the beach this afternoon and into the evening to reconsider."