Tropical Cyclone season for New Zealand runs from 1 November to 30 April. During this time, MetService issues track maps to show where a tropical cyclone has been and where it’s expected to go next.

Each map tells two stories: the past and the future.

Each year, about nine tropical cyclones form in the South Pacific between November and April. Of these, three or four move south out of the tropics, and most of them transform into a different kind of weather system before they reach New Zealand.

What do Irene, Rae, Tam, and Osai all have in common?

They’re all names of past South Pacific tropical cyclones. But who decides on these names? And why name them at all?

Few weather events are as terrifying or as powerful as a tropical cyclone. MetService have tropical cyclone specialists in its National Forecasting Centre who always have their eyes on the Tropics and issue appropriate and timely warnings based on expertise, weather observation network and weather modelling tools.