The Bureau of Meteorology (BoM) said the coastline from the NSW Central Coast to Queensland’s Sunshine Coast has been hit by “abnormally high tides”.
“Places like Byron Bay have seen average waves of five metres,” meteorologist Agata Imielska said.
“The highest wave we saw in Byron Bay was 10 metres.”
NSW Police Superintendent Murray Reynolds said the dangerous surf conditions have caused an increased risk of water tragedies.
“Just in the last week we’ve seen a number of tragic incidents that have resulted in the death of people in and around or waterways,” he said.
“One of the most difficult aspects of policing is investigating fatalities and understanding the outcome was entirely preventable.”
Marine Rescue NSW has carried out 560 rescues in December which is an increase of more than 29 per cent compared to December 2020.
Authorities have urged holiday goers to implement water safety such as wearing a life jacket, not entering the water if you can’t swim, and swimming between the flags at beaches.
The massive swells and dangerous winds have forced the closure of multiple beaches along the Gold Coast and Coffs Coast in NSW.
George Shales, Surf Life Saving NSW, said the “large swell conditions and high tides is making it extremely dangerous”.
“In terms of beaches today we’ve got 146 beaches that should be open, 80 per cent are closed today,” he said.
Ex-tropical cyclone Seth has caused dangerous surf conditions, the BoM said.
The hazardous surf conditions are expected to peak on Wednesday morning and then ease.
However as the dangerous surf eases, NSW will see the return of thunderstorm risks, Ms Imielska said.
“The thunderstorm risk will be of particular concern for the southern part of the state from Wednesday into Friday,” she said.
Much of the country will also be hit with sweltering temperatures today as a three-day heatwave hammers multiple states.
The Bureau of Meteorology (BoM) said “areas of severe heatwave conditions are forecast to cover the west of Queensland, the south and centre east of the Northern Territory, and a small area is forecast near Giles in Western Australia”.
Western Australia is forecast to reach 49C later in the week.
Currently Seth is sitting about 250-kilometres south east of Brisbane but the system is weakening.