"As they say, it's the calm before the storm," said Fiji Meteorological Service director Alipate Waqaicelua.
"There's sunshine, blue skies and calm seas but we've been advising the public things are going to change tomorrow."
A state of disaster was declared in Samoa after the cyclone hit, with people being evacuated across the islands.
It was now turning west and by tomorrow was expected to close in on the islands of Wallis and Futuna, bringing strong winds, heavy rain, and big swells, before moving towards Fiji, said Waqaicelua.
"At this stage the track is going to be just to the north of Fiji but from Monday night it is going to start heading towards the south and that is when it is anticipated to move over the islands in the western parts of Fiji."
It could then possibly hit the western side of the island where the international airport and towns are located, he said.
Waqaicelua said by the time it reached Fiji it was possible the cyclone would develop into a category five - a level reserved for the most severe tropical cyclones and which was "quite rare", he said.
Fijians are being urged to take all possible precautions as the nation braces itself.
Residents were listening into regular updates about the cyclone's path.
A spokeswoman for Capricorn Hotel in Suva said they were unsure what to expect.
"The weather is calm at the moment but we don't know about Sunday or Monday so fingers crossed we're okay."
Fiji's self appointed prime minister Commodore Frank Bainimarama urged every Fijian citizen to take the "impending disaster" seriously and to restrict their movements and refrain from unnecessary travel.
