Fiji's first tropical cyclone of the year has killed one person and left behind a swathe of damage.

Relief workers say a 30-year-old woman was swept away by flood waters while attempting to cross a flooded bridge near the western town of Nadi late Tuesday, as her husband and three children watched helplessly.

Cyclone Cliff grew more powerful on Wednesday, causing widespread damage in Udu, the northernmost point of the archipelago's second largest island, Vanua Levu.

Close to its centre, the cyclone packed winds of up to 95 kilometres an hour, with gusts of up to 140 kilometres an hour, the Fiji Meteorological Service said.

Radio operator Samisoni Levu told commercial radio that strong winds damaged houses and other village buildings.

"Heavy rain caused a landslide at the village school and our children were lucky, as it happened after we sent the children home early," Mr Levu said.

The cyclone also caused major damage to homes and crops on the nearby Taveuni island and in Vanua Levu.

Communications with the Lau group of islands in the east of the country had been difficult in the storm and the extent of damage was unknown.

The cyclone was due to head east towards Tonga.