Tropical cyclone is the catch-all term for the powerful, spinning storms that feed off warm oceans and the strength of which is determined by wind speeds. The strongest are known as hurricanes in the Atlantic and typhoons in the Western Pacific and simply tropical cyclones in the South Pacific.

The unusual activity is "a lot to happen at once, but not unprecedented," an atmospheric science professor said.

Millions of people in the South Pacific are reportedly experiencing an "unusual" weather occurrence as three cyclones spin out of control as the region hits peak storm season.