New Zealand has a "normal to elevated" risk of an ex-tropical cyclone affecting the country this season, weather forecasters warn.
NIWA and MetService's outlook found between six and 10 tropical cyclones could occur in the Southwest Pacific between November and April, at least three of which will be severe.
On average, at least one ex-tropical cyclone passes within 550km of New Zealand each year, bringing significant rainfall, extreme winds, hazardous marine conditions and coastal damage.
"At least three severe tropical cyclones (category 3 or higher) might occur anywhere across the region, so all communities should remain prepared," NIWA said.
Modelling suggests wind speeds could reach at least 119 km/h.
If an ex-tropical cyclone comes close to the country, there is a near-equal chance it will track to either the east or west of the North Island.
Forecasting also shows interactions of a "decaying storm system" can occur with the northern South Island, NIWA said.
"New Zealand should also remain vigilant as the season unfolds," the assessment said.
Earlier this year, Cyclone Fili left a trail of destruction across Wairoa and Tairāwhiti, Gisborne.
A combination of strong winds and rainfall caused flooding, power outages, tree falls and road closures on the east coast of the North Island.
This year also brought a spate of extreme and unusual weather events, including snow across the country last week and severe flooding around the motu.
When dangerous weather is forecast, Metservice and NIWA are urging people to heed the advice of their local meteorological service, civil defence, or disaster management office.
