A tropical cyclone forming near the Pacific Islands next week could impact New Zealand just days before Christmas, Weather Watch has warned.
Modelling shows the weather system will build between Vanuatu and Fiji in the middle of December before drifting west to northern parts of the Tasman Sea. From there, it could pivot south towards Aotearoa.
Weather Watch says the cyclone should remain away from our shores, but should it head deep enough into the Tasman Sea its impacts will be felt on our shores and "pose some risk" to Kiwis.
However, it also acknowledges it's early days and that the modelling is not necessarily a "locked-in forecast". It says the cyclone could just remain at sea and have no damaging effects on New Zealand.
"With La Niña, it's only been a matter of time before we saw a likely cyclone develop to New Zealand's north, up in the South-West Pacific tropics," Weather Watch says.
"Around the time this storm is likely to develop, a powerful and protective high-pressure belt should be over New Zealand. So the question may be more about what happens heading towards the end of the third week of December... as this big high moves away to the east.
"It looks as though this high over New Zealand may be the likely controlling factor for any tropical lows coming our way."
The South Pacific Ocean recently moved into tropical cyclone season. The season lasts from November 1 to April 30, and comprises about 10 tropical cyclones in that period - only one of which will affect New Zealand on average, MetService says.
Last week, NIWA revealed in its seasonal climate outlook that New Zealand would be at "elevated" risk of significant rainfall, damaging winds and coastal inundation during the tropical cyclone season.
The forecaster said Kiwis would be in store for a dry start to summer, but that "moist, subtropical disturbances" could bring heavy downpours and flooding to New Zealand as it goes on.
The forecaster also said air temperatures would be above normal throughout the country, alongside a marine heatwave and elevated humidity levels in the North Island.
