South Pacific tropical cyclone season outlook

The tropical cyclone season runs from 1 November to 30 April

Average number of cyclones likely in the western Pacific Ocean

  • Near average number of tropical cyclones are expected in the western South Pacific region this season.
  • ENSO-neutral to weak El Niño-like conditions in the tropical Pacific Ocean have influenced this year's tropical cyclone outlook.
  • Most climate models indicate that neutral conditions are likely to persist into 2019, although the risk of El Niño is still significant.
  • Near-average cyclone numbers are also likely for the eastern South Pacific but model accuracy is very low.

The South Pacific tropical cyclone season typically extends between 1 November and 30 April. The average numbers of tropical cyclones during the season in the western and eastern regions are seven and four respectively. Tropical cyclones affect Pacific island countries in most years and can impact coastal regions even when they remain  well offshore.

 * Long-term average number of tropical cyclones, calculated using data from 1969–2017, may change slightly from one year to the next as a new season of data is added to the calculation.

This outlook is based upon the status of the El Niño–Southern Oscillation (ENSO) during the preceding July to September. Eastern tropical Pacific Ocean sea surface temperatures have been warming all year and are now above average, although they have yet to exceed El Niño thresholds. The Southern Oscillation Index recently exceeded El Niño levels but other atmospheric indicators of ENSO (trade winds and cloudiness in the central Pacific) remain at normal levels. Eight international climate models surveyed by the Bureau forecast Eastern Pacific Ocean temperatures to remain above average throughout the summer, with three out of eight models predicting an El Niño to eventuate during the season.

The statistical model used for this outlook has a high level of accuracy predicting cyclone numbers in the western region, but a very low level of accuracy for the eastern region. This outlook is for the southern hemisphere tropical cyclone season which runs between 1 November and 30 April.

Product code: IDCKSPTCSO