Cyclone Donna continued to lash Vanuatu's northern islands for a third straight day on Sunday, hampering efforts to send assessment teams and aid to remote areas.
The cyclone, which remained a category four, lingered for much of Saturday and Sunday about 300 km off the western coast of Torba province.
The Vanuatu Meteorological Service said the cyclone had sustained winds of 185km/h at its centre, gusting as high as 235km/h.
A forecaster, Jerry Timoteo, said the cyclone's size meant most of the country would feel its effects, particularly the worst-hit Torres islands, which had been battered for days.
For Torres, the service said the island group would continue to bit hit by winds gusting as high as 160km/h well into Sunday night.
Communication with Torres was proving difficult, said Shadrack Welegtabit, the director of the Disaster Management Office, but preliminary reports of damage to houses and food crops had emerged.
Mr Welegtabit said the cyclone's lingering nature was frustrating the response effort.
"We cannot do any assessment now - both aerial assessment and ground assessment - with the system hovering to the north," he said. "There is still strong gale force winds around the provinces so it's not safe to send any aircraft or boat in at this stage."
Mr Welegtabit said disaster authorities and aid agencies were standing by with people and supplies ready to be deployed to the north as soon as it was possible, which could be on Monday.
The Meteorological Service's Mr Timoteo said Cyclone Donna was expected to slowly move south later on Sunday and gradually weaken.
While the country's more populous southern islands were likely to be spared a direct hit, he said, most of the country would still experience severe weather well into next week.
"Heavy rainfall and flash flooding was also expected over Torba, Sanma, Malampa and Penama provinces, especially over low lying areas and areas close to river banks," said Mr Timoteo, adding that landslides and coastal flooding was also expected.
On Vanuatu's largest island, Espiritu Santo, some 500km south of Torres, the country's second-largest town, Luganville, was being locked down in anticipation of Donna's passing on Sunday night.
RNZ International's Vanuatu correspondent said major shops were being told not to sell any more than what was already on their shelves in order to ensure a food supply for after the cyclone.
While the cyclone was forecast to pass some 200km away from Santo, already bad weather was expected to worsen as Donna made its gradual passage south.
Already, there were reports of food gardens being destroyed on the island, and residents in Luganville were being told to boil their water in case of contamination. Evacuation centres had been opened on the island.
To the south, authorities in New Caledonia were warning people to remain vigilant, with the cyclone expected to reach that territory early next week, although in a weakened state.
There, the government declared a cyclone "pre-alert", with residents urged to prepare for the cyclone's arrival, particularly on the Loyalty Islands.
In a statement, the civil security department said Donna was expected to bend its trajectory toward the territory, with wind and rain forecast to pick up from Sunday.
RNZ International will broadcast news and cyclone warnings to Vanuatu via shortwave and AM radio. Information on how to listen can be found here.