The Nadi Weather Office says the whole of Fiji should be on alert as the weather system currently 1020 kilometers north-northwest of Labasa is now a tropical depression and is expected to intensify into a tropical cyclone tomorrow afternoon.
A heavy rain alert is now in force for Vanua Levu, Taveuni and nearby smaller islands, Northern Lau Group and the Yasawa Group.
A strong wind warning remains in force for land areas and waters of Rotuma.
Director of Meteorology, Misaeli Funaki says this system will move southwards and come close to Fiji and when it forms into a cyclone, it will be named as Cyclone Sarai.
Funaki says while majority of the models are projecting for the system to move just to the west of Yasawa and Mamanuca Groups, some other models are showing that the Cyclone could come over Viti Levu later Friday.
He says as the system is expected to move closer to Fiji on Friday, people should start preparations after merry making on Christmas Day.
The Nadi Weather Office says rain and thunderstorms will start developing over northern, central and eastern parts of the country from tomorrow.