Tonga could take six months to recover from what's being called the worst storm there in 60 years.
The storm, which was briefly upgraded to category five yesterday before being lowered to category four again, is to the southeast of Vanuatu and is set to lose power as it passes to the south of New Caledonia.
Neither Vanuatu nor New Caledonia are expected to be hit hard by the storm, and it is expected to fall to category three before passing over Norfolk Island.
It appears the worst damage is already done however, after the storm made landfall in Tonga on Monday night as a category four cyclone, ripping roofs off houses, destroying crops, and destroying a church as well as Parliament House.
Thousands of people are still unable to return home and the government has confirmed three people were seriously injured by the cyclone.
The Red Cross said water and electricity are still out for many people in the island group.
Its local adviser, Poli Kefu, says almost every second house visited had damage from the cyclone.
"I think it will take more than another six months to recover for Tongatapu, which is the main island," Mr Kefu said.
"This is more than likely the first time in 60 years for them to experience this very powerful, damaging cyclone."
Mr Kefu says people in Tonga should drink only boiled or bottled water, to avoid sickness.
Matangi Tonga news editor Mary Fonua told Morning Report over 1100 homes were damaged in the greater Nuku'alofa area.
She said more than 4000 people went to the Tongatapu evacuation centres during the cyclone, and many of them were still there.
"Before they can get the grid up and running they've got to get the power poles up and off the roads
Power, water the priorities
Graham Kenna from Tonga's National Emergency Management Office said conditions were improving and more supplies were coming in.
"The priority is to get the electricity going, mostly because it is used for water pumps and secondly it would be to get the reticulated water moving in the capital.
He said power had been restored to the hospital and the water board were starting to get some facilities up and running, but for a lot of people another problem was they no longer had anywhere to live.
"We started some distributions yesterday, just urgently needed shelter for the families that have lost everything we've been able to get out some family kits for them so at least they'll have some shelter overnight.
"It has rained overnight, and it's making things very very difficult for people who don't have shelter.
"That's our focus again this morning for our other teams is to get shelter out to some people.
He said Australia and New Zealand were sending generators along with supplies to help get the power running again, and there seemed to be enough fuel to run them.
"Fortunately we have enough fuel, we think we have enough fuel to last until Wednesday of next week and there is a tanker due in ghere on Monday of next week."
Tonga food supplies secure in short term
New Zealand's acting high commissioner to the kingdom, Elena Procuta, said early assessments conducted by the Ministry of Agriculture after the cyclone show there is enough food for the short-term.
She said root crops like taro, cassava and yams have not been badly damaged and they could meet immediate needs.
However there were also concerns for tree-grown staples like plantains, breadfruit and bananas.
"The government is still working out how they're going to manage the food security situation but an early assessment might be that it's not as devastating as it could have been. They've got sufficient for the short term."