People in Vanuatu's southern Tafea province are being urged to seek shelter immediately as cyclone Ula inches closer to the country.
In its latest warning, the country's meteorological service says the category four system is currently about 235 kilometres east of Tanna, and 185 kilometres east-northeast of Aneityum.
The cyclone is moving in a southwest direction at 11 kilometres an hour, with winds of 165 kilometres an hour at its centre.
Ellen Luke, a forecaster at the Vanuatu Meteorological Service, says the cyclone is expected to pass close to the islands of Aneityum and Futuna, although it's hard to predict just how close.
Ms Luke says the entire province can expect damaging gale-force winds, torrential rain, and very rough to phenomenal seas.
The National Disaster Management Office on Sunday issued a red alert for Tafea province. Ms Luke says this means residents should seek shelter.
"If the cyclone is moving closer to the islands then it will be causing some damages, so the advice is to seek very good shelter in some very good houses to prepare themselves for the cyclone as it's moving close."
Ellen Luke says the cyclone is moving erratically and could hit some islands directly.
Tafea province was one of the worst affected by the category five Cyclone Pam, which struck in March last year, and has been struggling with drought caused by this year's El Niño system.
Last weekend, Ula caused minor damage in northern Tonga and Fiji's Lau group as a category two system, but it has strengthened again in the past 48 hours.
To the southwest, New Caledonia's government has issued a cyclone pre-alert for the entire territory.