Holidaymakers in Fiji can only sit and wait out a tropical cyclone still hammering the small island nation.

Tropical Cyclone Sarai - upgraded to a Category 2 event yesterday - is averaging winds of up to 100km/h with momentary gusts of up to 140km/h close to its centre, authorities say.

The latest update from the Nadi Weather Office, as at 6am, was that it was moving at a speed of up to 17km/h and people should expect an increase in "damaging gale force winds."

It is moving away from the mainland, and images today show damaged homes and trees down in low lying areas. There are not yet any reports of injuries.

Late last night, the Fiji Meteorological Services Office issued a storm warning in full force for parts of the country.

Authorities were working to evacuate people living on coastal areas and evacuation centres were being set up to help those affected.

"More evacuation centres are expected to be activated as people living in low-lying areas and coastal areas have started experiencing damaging winds and heavy rain," a media statement said.

Flights cancelled again

Flights from Auckland International Airport and any due to arrive from Nadi are all cancelled today.

On the airport's website, 10 flights due to touch down throughout today and the early hours of tomorrow have been cancelled.

Thirteen flights due to leave Auckland for Nadi have also been cancelled.

The airlines affected include Air New Zealand, Fiji Airways, Qantas, Singapore Airlines and Cathay Pacific.

A statement from Air NZ encouraged passengers affected to check its Travel Alerts page for updates, information on rebooking and the flexibility the airline is offering in light of the situation.

"We apologise to customers for the inconvenience caused and thank them for their understanding at this time," the airline said.

A New Zealand couple staying on Mana Island - to the west of mainland Fiji - described "intense" winds and heavy rains when the tropical cyclone arrived yesterday.

Melonie Sheppard said they were in lockdown in their room at the resort they are staying in.

"We're being hammered by intense winds and horizontal rains. The resort is providing packed meals and water direct to rooms when they can.

"We are due to fly home [tomorrow] at 2pm, so keeping all fingers and toes crossed that ferry and Air New Zealand services will be up and running again by then," she said.

Just before 5pm yesterday, she said the torrential rain and "incredibly strong winds" had lasted for about four hours.

"Wind is howling and tree debris flying about, doors and windows shaking, huge waves rolling into shore.

"Water now leaking into some rooms - it's a bit scary at times."