Fiji's metservice says the tropical depression currently battering the country is expected to develop into a cyclone later today.
Nearly eight thousand people are sheltering in evacuation centres, following two days of strong rain and winds that have caused flooding in the west of Viti Levu.
Three people have been confirmed dead and a state of natural disaster has been declared.
A forecaster, Terry Atalifo, says early this morning the system was over Vanuatu, about 1,000 kilometres west of Nadi, and is moving Southeast at about 25 kilometres per hour.
He says on that track, it is likely to miss Fiji, but will still bring gale strength winds and heavy rain.
A gale warning and severe flood warning remain in place for much of Fiji.
Warnings are also in place for parts of Vanuatu, with its metservice saying damaging gale force winds of 70 kilometres per hour will continue to affect Southern Penama, Malampa, Shefa and extending to to Tafea province.
It says very rough seas with heavy swells are expected over northern and central waters of Vanuatu, and heavy rainfall and flooding is expected.