Severe weather, flood and hazardous surf warnings have been issued for the Far South Coast.
According to the Bureau of Meteorology, a trough deepening near the coast is expected to bring periods of moderate rain on Tuesday, possibly becoming heavy at times.
Rainfall intensity may be increased by the development of small low pressure circulations within the trough, and by thunderstorm activity.
Heavy rain may lead to flash flooding along the Far South Coast, and water levels could reach or exceed the highest tide of the year during high tide between about 10am and 11am on Tuesday morning.
The Bega River catchment is likely to be affected.
Surf and swell conditions are expected to be hazardous for rock fishing, boating, and swimming along the coast.
The risk of heavy rainfall is expected to ease by the end of Tuesday.
The State Emergency Service advises that people should not ride or walk through flood water, keep clear of creeks and drains and if you are trapped by flash flooding, seek refuge in the highest available place and ring 000 if you need rescue.
For emergency help in floods and storms, ring your local SES Unit on 132 500.
NSW Police Force Marine Area Command advises people to avoid the water walking near surf-exposed areas.
Rock fishers should avoid coastal rock platforms exposed to the ocean and seek a safe location sheltered from the surf.
Boaters planning to cross shallow water and ocean bars should consider changing or delaying their voyage, and boaters already on the water should carry the appropriate safety equipment and wear a lifejacket.