Tonga is bracing for a severe hit from a tropical cyclone that has the potential to reach category 5 in strength - bringing winds of up to 300km/h.
Cyclone Winston is forecast to reach the Vava'u group of islands late tomorrow and expected to stay through to Saturday.
MetService duty meteorologist Micky Malivuk said there was potential for the tropical cyclone, which was tonight category 4, to reach a category 5 status - the most dangerous and destructive of all storms.
Regular weather warnings in the Pacific region were being issued by the Fiji Meteorological Service, Mr Malivuk said.
The advice to locals was to "brace for impact".
"The other areas of Tonga will experience high seas and heavy rain too. But Vava'u, specifically, will get the strongest winds," he said.
"With strong winds, you have to brace all loose items because a lot of the buildings over there are not structurally sound like they are here, to withstand strong winds."
Vava'u - north of Tongatapu, where the capital Nuku'alofa is - has already bore the brunt of the same cyclone earlier this week.
Evacuation centres were set up at local churches to help villagers hunker down.
The Matangi Tonga newspaper reported trees falling and roofs collapsing. No injuries have been reported.
Despite the cyclone system passing through, it has effectively done a U-turn in the past few days.
A total of 90 New Zealanders are registered as being in Tonga - two are registered on SafeTravel as being in Vava'u.
A Ministry of Foreign Affairs and Trade spokeswoman said all the New Zealanders had been contacted by the NZ High Commission in Tonga and their well-being confirmed.
New Zealanders there are being urged to register their details with MFAT on the SafeTravel website.
Mr Malivuk said Cyclone Winston is forecast to leave Tonga later on Saturday and head towards Fiji.
At the moment, the weather system is tracking to pass over the southern islands of Fiji.
However, it is still expected to be a category 4 cyclone and locals there are also being warned to prepare.
New Zealand aid agencies are already on standby to help provide assistance to the Pacific nations if need be.
Oxfam NZ's Pacific humanitarian manager, Carlos Calderon, said: "Cyclone Winston is the second to hit Tonga this year. Oxfam is supporting its community partners and we are ready to reach out with emergency supplies to those affected, should they need our help.
"With support from the New Zealand Aid Programme, our water equipment is on the ground and ready to go."
Those supplies would be able to provide up to 8000 people with safe water to drink and use.
The MetService said tonight that at this stage, the cyclone system was not expected to head towards New Zealand.
However, wild weather caused havoc in some parts of New Zealand today and last night.
A front moving over the west of the country brought huge amounts of rain and strong winds to both islands.
There was flooding in several parts of the South Island and thunderstorms in Central Otago - where three houses were struck by lightning.
MetService meteorologist Peter Little said the unsettled weather would ease quickly by the weekend.
A ridge of high pressure over the country will bring fairly settled weather for both the North and South Islands during the weekend and through to next week.