A low-pressure system is sweeping through multiple states and is set to affect NSW, Tasmania, Victoria and South Australia.

Powerful surf will batter the central and southern parts of NSW, with waves of 3-4m expected to hit on Friday and Saturday.

In Sydney, wave heights are expected to peak at 4.5m over the weekend, creating rough seas off the city’s coast.

The Bureau of Meteorology has issued a hazardous surf warning for much of the NSW coast.

The warning covers the Byron Coast, Coffs Coast, Macquarie Coast, Hunter Coast, Sydney Coast, Illawarra Coast, Batemans Coast and Eden Coast.

While the waves are expected to be large, they will also be “deceptively powerful”, according to Weatherzone.

NSW Police and the Marine Area Command are advising swimmers to say out of the water and avoid walking near surf-exposed areas.

Rock fishers are being urged to avoid coastal rock platforms exposed to the ocean and seek a location that is sheltered from the surf.

“Boaters planning to cross shallow water and ocean bars should consider changing or delaying their voyage,” the warning states.

The bureau has also issued a marine wind warning for strong winds and gale warnings for the Eden Coast and Batemans Coast.

Victoria has also been issued a marine wind warning summary for the Central Coast, Central Gippsland Coast and East Gippsland Coast.

Wild weather warnings remain in place for Queensland after parts of the state were hit with flash floods, forcing residents to swim for their lives.

Days of rain and wind swept through the state’s southeast from Laidley in the Lockyer Valley west of Brisbane up to the Sunshine Coast.

Emergency services were forced to launch dozens of rescues for families trapped in cars and homes.