A Damaging Heavy Swell Alert is now in force for Southwest Viti Levu waters, the Yasawa and Mamanuca waters, Kadavu Passage, Koro Sea and Southern Lau waters.
The Nadi Weather Office says a high-pressure system to the far southwest of Fiji is expected to generate and direct damaging heavy swells towards Fiji waters from later tomorrow.
It says damaging southwesterly swells are expected to develop, with wave heights reaching up to four metres over open waters.
Wave periods of up to 16 seconds are also forecast from later Saturday.
People travelling by sea and those living or carrying out activities in affected coastal areas should remain alert to changing sea conditions.