CYCLONE Pam has been upgraded to the strongest storm category possible as it batters New Zealand's neighbours and heads south.
Northeastern parts of New Zealand were advised to brace for destructive weather in days ahead as a result of Pam.
Pam has been upgraded to a Category 5 storm this morning.
"Using the most recent data the system is forecast to pass just to the east of East Cape during Monday," the MetService said yesterday evening.
"However, there is still a large degree of uncertainty in the exact path of the cyclone and although the centre may not pass over New Zealand, severe weather is likely to affect parts of the country - especially the northeast of the North Island."
People in and around Gisborne, the East Cape and Hawke's Bay should keep an especially close eye on weather forecasts as Pam approached.
"There's still a fair bit of uncertainty as to how that system will move. But it does look like we are going to find some pretty damaging conditions as we head through to the start of next week," meteorologist John Law told TV3 this morning.
MetService Meteorologist Georgina Griffiths last night said the eastern North Island could possibly get "the full trifecta" of impacts, these being damaging seas along the eastern coastline, gale to severe gale south-easterly winds, and the possibility of heavy rain.
WeatherWatch.co.nz reported yesterday evening that winds around the upper North Island, north of Auckland, were already caught up in the flow of Cyclone Pam, a few thousand km away.
"This is a monster storm - we don't say that lightly, a cyclone with this energy only comes down to New Zealand about once every 20 or 30 years," WeatherWatch analyst Philip Duncan told NewstalkZB
"It's a positive sign that most reliable computer models are suggesting Pam will sideswipe north eastern New Zealand out to the east - but all North Islanders north of Waikato and Hawkes Bay should be closely monitoring the regular updates across the next few days."
The United Nations Office for the Coordination of Humanitarian Affairs (OCHA) said Pam battered the Solomon Islands as it passed to the country's east.
OCHA warned some island nations faced more trouble ahead after Pam as a separate tropical cyclone called Nathan intensified.
As Pam turned south, Nathan, already in the Coral Sea as a Category 2 cyclone, was expected to intensify and turn towards Papua New Guinea, the Solomon Islands and possibly Vanuatu.
"This could have devastating effects for communities living in areas that have already experienced prolonged rains and other impacts from [Cyclone] Pam," OCHA said.
The fifth leg of the Volvo Ocean Race from Auckland to Itajai in Brazil was due to start on Sunday, but race organisers say the earliest the boats will depart is 2pm Monday. A final decision will be made tomorrow.
Vanuatu meteorologist David Gibson, based in Port Vila, said it was the strongest cyclone to form near Vanuatu in almost 30 years. Cyclone Uma in 1987 caused widespread damage and loss of life.
Mr Gibson said the northern and central islands of Vanuatu were on alert, businesses had shut and evacuation centres were prepared.
The cyclone was expected to stay around northern Vanuatu islands today and move to the main island Efate, where the capital Port Vila is located, late tonight.
He said the warning covered "heavy raining and flooding of low-lying areas and areas close to riverbanks" and "damaging winds".
A New Zealander in Vanuatu said expatriates acted quickly to take cover from the storm.
Jeff Brown told Radio New Zealand he moved his family from a house to a motel near the capital Port Vila, fearing the house they lived in would not withstand the cyclone.
Oxfam's Vanuatu country director Colin Collett van Rooyen said it was difficult to know how seriously local people were taking the warning of a category 5 storm.
"I think people are prepared for a weather event, but I'm not too sure about the extent to which they're prepared for the force of this particular event," he told TV3's Firstline from Port Vila.
People had told him 'nobody really knows what a category 5 does', he said.
"And I think that's a huge challenge, that people are prepared for a weather event, if they're aware of it, but not necessarily the extent, because that is something of a mystery."
Some people were already moving to cyclone shelters, he said, but communicating the warning of the on-coming storm was among the challenges facing aid workers in the Pacific island nation.
"One of the problems, or challenges, is getting information out to people about cyclone centres and also to get people to understand the severity of a category 5 cyclone in Vanuatu," he told the broadcaster.
"People are boarding up or have boarded up, their houses if they have cyclone shutters, businesses have shuttered their buildings up in the main, and information has been put out where possible.
"At the moment, regular radio bulletins, regular text messages across the two networks that we have here, and encouraging people to talk with their neighbours, their family, and to identify where they need to move to and to get supplies in because we don't know how long they might need to be in the shelter before they can actually get out safely."
His biggest fear for the impending storm was that people "don't actually understand the extent to which it is serious and don't prepare sufficiently", he said, followed by the possible damage to infrastructure.