Surfers flocked to Illawarra beaches on Monday as powerful swell pounded the coast.
Subscribe now for unlimited access.
$0/
(min cost $0)
or signup to continue reading
Wave heights reached more than four metres off Port Kembla during the morning as a southern swell made its presence felt - albeit unexpectedly.
Weatherzone meteorologist Ben Domensino said a large and powerful groundswell originating from a system travelling to the south of New Zealand arrived on Australia's east coast earlier than expected.
Waves at some of Sydney's most popular beaches were reaching double overhead on Monday morning, or about twice the height of an average person, Mr Domensino said.
It was a similar situation off Wollongong, where a maximum wave weight of 4.27 metres was recorded by the Port Kembla wave buoy at 9am - up from 2.49m at 6pm on Sunday.
The peak wave period, which measures the power of the swell, at Port Kembla more than doubled on Monday morning - from 8.5 seconds at 3am to 17.4 seconds at 4am. It was still 17.4 seconds at 9am.
Data recorded by the Sydney wave buoy showed the peak wave period there was near 20 seconds.
“This long-length wave period is rarely seen on the NSW coast and is more typical for coastlines that are exposed to broad expanses of ocean, like Hawaii or southwest facing coastlines of southern Australia,” Mr Domensino said.
“These longer period swell travel more quickly than lower period swells and maintain their size and energy for many thousands of kilometres if uninterrupted by land.”
The Bureau of Meteorology has warned surf conditions on Tuesday may be more powerful than they appear.
Conditions are expected to be hazardous for coastal activities such as rock fishing and swimming.