The Nadi Weather Office says rain and thunderstorms will start developing over northern, central and eastern parts of the country from tomorrow.
A Tropical Disturbance still lies to the far north of Fiji and is expected to gradually track southwards.
Associated trough of low pressure is expected to affect the country from tomorrow.
The Nadi Weather Office says the tropical disturbance is expected to gradually intensify and upgrade into a depression and has high chance of developing into a tropical cyclone.
The disturbance remains slow moving to the north of Rotuma and is expected to move south towards Fiji by Friday and bring heavy rain and strong winds.
They say the system is forecast to track just to the west of Yasawa and Mamanuca Group before turning and moving southeastwards tracking south of Kadavu then towards southern part of Lau Group.
Director of Meteorology, Misaeli Funaki says at the moment, the main areas of concern for them are the western parts of Viti Levu which is from Sigatoka to Rakiraki, northern parts of the Northern Division, Yasawa and Mamanuca Group, Kadavu and Southern Lau.
Funaki adds that the system is anticipated to leave Fiji waters by Sunday.
