Fiji is bracing for another powerful tropical cyclone as the island nation expects wind gusts of more than 150km/h.

Cyclone Zena is expected to make landfall overnight, but dangerous weather conditions have already claimed the lives of two people.

Nadi International Airport is also closed, trapping foreigners in Fiji as the category three cyclone approaches.

One 19-year-old student died while trying to cross a river with friends, while the body of a 70-year-old man was also found in the same river area near Nadi, ONE News understands.

Fijian police enforced a curfew this afternoon, with the town of Rakiraki described as a ghost town by the Fiji Times.

Businessman Simadri Narayan, who lives in the town area, said the Vaileka River had broken its banks.

Cyclone Zena was upgraded to a category three cyclone this afternoon as it gains strength and moves towards Fiji, senior weather forecaster Misaele Funaki told the Fiji Times.

All schools across the Pacific Island nation are closed today, the Fiji Government advises on its Facebook page.

"Stay safe people and always look out for each other," the Government posted.

Zena is situated southeast of Fiji and is intensifying, Fiji Broadcasting Corporation reports.

Nadi town is currently closed due to widespread flooding with more than 3,500 residents forced into evacuation centres, many from Nadi.

All major rivers in Fiji are expected to experience flooding and continuous rain is forecast over the next 48 hours, Fiji Broadcasting Corporation reports.

The head of shelter charity Habitat for Humanity Claire Szabo was also urging Kiwis to support its disaster response fund, as families in Fiji, brace for the second tropical cyclone in six weeks.