A tropical depression several hundred kilometres northwest of Nadi in Fiji is expected to become a category one tropical cyclone by midday Friday.
The depression is moving south-southwest and intensifying.
On its current path, it is expected to stay to the west of Fiji.
But disaster management officials in Fiji said, because of the associated trough of low pressure, a flood alert remained in force for all low-lying areas and small streams throughout the country.
Heavy rain and wind warnings were also in place for all of Fiji and flooding of major rivers was possible.
Winds could gust up to 60km/h.