A south easterly swell is expected to reach two to three metres at its peak, with a swell period around 15-17 seconds.

These conditions will be hazardous for coastal activities including swimming, surfing and rock fishing.

Conditions are expected to ease overnight on Saturday, April 19 however the swells will stay around 1.5-2m on Sunday, April 20.

“With the onset of these dangerous condition we strongly encourage swimmers to follow all safety warnings and avoid entering the water unless there is an active patrol on duty, which will be signified by the red and yellow flags,” said Andy Kent from SLSNSW.

“If you are ever unsure about the conditions, have a chat to one of the lifesavers or lifeguards on duty before entering the water.”

At the beach, swimmers are advised to:

* Always swim between the red and yellow flags

* Read the safety signs

* Ask a lifesaver/lifeguard for safety advice

* Learn how to identify a rip

* If you need help, stay calm and attract attention

* Always wear a lifejacket while rock-fishing

* If witnessing an in-water emergency call police on 000

For full details on which beaches are patrolled and patrol times (including over the winter months) go to Beachsafe, which is also available as an iPhone app.