Cyclone Keni is Category 3 storm and is expected to be closest to the islands from midday today.
The Fiji weather office is expecting Keni to pass south of Nadi before making landfall over the southern island of Kadavu.
People are being told to expect destructive winds of up to 170 kilometres an hour.
The government says they need to prepare a three day family disaster kit, strengthen their homes, be ready for power cuts and evacuate if need be.
It's the second cyclone to hit Fiji in just over a week after Cyclone Josie left six people dead over Easter.