Residents at Northern Territory have been advised to prepare necessary precautions as a cyclone could potentially ram into the region on Wednesday.

Relief and rescue operations meantime are racing against time to reach Tonga, following the devastation that Category 5 Cyclone Ian brought on the low-lying island over the weekend.

The Bureau of Meteorology said the tropical low pressure system weather is currently in the Arafura Sea just off Australia's north coast. It is moving in a westerly direction. Scientists said it has a 20 to 50 per cent chance of developing into a cyclone.

"If the low is located sufficiently over water, there is a moderate chance it could develop into a tropical cyclone on Tuesday night," the bureau said on its Web site.

And "if it keeps on the track it may become a cyclone on Wednesday," Chris Davies, BoM duty forecaster in Darwin, said.

If it develops, it would be the fourth cyclone to hit Australia's northern region this season. Meteorologists forecast it would be a Category 1 storm. It would make landfall either late Tuesday or early Wednesday around the west coast of the Northern Territory.

Flood warnings have been raised for the districts in Darwin-Daly, Arnhem and Roper-McArthur.

The weather system is expected to grace over Cobourg Peninsula or Tiwi Islands on Monday night.

Over the weekend, at least 8,000 people in Ha'apai islands were affected as Category 5 Cyclone Ian's hurricane-force winds rammed and caused significant damage to islands. At least one has been confirmed dead. Island Lifuka bore the brunt of the storm.

"We haven't had any further reports of any deaths, which is very good indeed, and looking at the amount of devastation it was a miracle that not more than one person has a loss of life," Leveni Aho, Tonga's director of emergencies, also told ABC.

Tu'i Ha'angana, governor of Ha'apai, has visited the area. ABC News reported the governor was devastated with what he saw. "The damage is so bad, he can see from one side of the island to the other."

Mr Aho said they have yet to establish full communication with 80 per cent of the Ha'apai island group.

"The picture comes to hand now, it was really bad," he said. "We have got some people sheltered in some of the evacuation centres, buildings and some of the churches."

Cyclone Ian was one of the worst cyclones to hit Tonga. Ha'apai unfortunately "is one of the poorest areas in Tonga, where the people have less resources to recover by themselves," Carlos Calderon, Oxfam Pacific humanitarian manager, told ONE News.

Most houses were flattened, roofs were off, trees and power lines were down, Tupou Ahomee Faupula, who works for Digicel, one of Tonga's two cellphone providers, told the Matangi Tonga Online.