A wave rider buoy located near Coffs Harbour registered maximum wave heights over 10 metres last night, according to Weatherzone.
Another buoy located off the coast of Sydney was hit by an 8.5-metre wave.
A hazardous surf warning is in place for Byron Coast, Coffs Coast, Macquarie Coast, Hunter Coast, Sydney Coast, Illawarra Coast, Batemans Coast and Eden Coast.
Surf and swell conditions are expected to be dangerous for coastal activities such as rock fishing, boating and swimming.
People should avoid going into the water and walking near surf-exposed areas.
A gale wind warning is in place today for the Coffs Coast, Macquarie Coast and Hunter Coast.
There is also a strong wind warning for Sydney enclosed waters, Byron Coast, Sydney Coast, Illawarra Coast, Batemans Coast, and the Eden Coast.
A strong wind warning is in place tomorrow for the Byron Coast, Coffs Coast, Macquarie Coast, Hunter Coast, Sydney Coast, Illawarra Coast and Batemans Coast.
Strong winds and big seas lashed the east coast yesterday, as swell rapidly built at Avalon and Newport on Sydney’s Northern Beaches.