The next high tide is at 3.42pm (Fiji Time) in Lautoka and 3.45pm (Fiji Time) in Suva.
National Disaster Management Director Vasiti Soko said the periods of heavy rain are expected to persist throughout the country until Sunday.
She said as of this morning, most river levels have already reached or are above their warning level.
Continuous heavy rain is expected to cause the rivers to burst their banks.
Soko said rivers that have already burst their banks are Rakiraki, (Nasivi) Tavua, Ba and Vitogo located on the main island of Viti Levu.
NDMO said it has received reports of flash flooding in the West and North and a landslip along Kings Road on the main island.
The Director said no evacuation centres have been opened but members of the public are urged to move to safety while it is still daylight, should the need to evacuate arise.
According to Soko, Police officers are on standby should the need for deployment arise.