Huge surf with waves exceeding five metres and flooding rains are expected to hit many parts of eastern NSW on Friday.
A severe weather warning issued by the Bureau of Meteorology is current for the Hunter, metropolitan Sydney, Central Tablelands and Illawarra and the South Coast regions.
Heavy rain is expected to cause flash flooding in the Hunter and parts of Sydney and the Central Tablelands on Friday.
Damaging surf conditions, with waves exceeding five metres, are likely to produce significant beach erosion between Newcastle and Port Hacking on Friday afternoon, and between Port Hacking and Moruya o n Friday night.
Surf Life Saving Australia recommends people stay out of the water and stay well away from surf-exposed areas.
SES spokesman Phil Campbell said there were 75 calls for help between Wollongong and the mid-north coast on Thursday.
And he added the worst of the weather was yet to come.