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 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 2020.
  • 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 four and seven 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 1969–2018, 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 cooled significantly since July and are currently close to average. The Southern Oscillation Index (SOI) was neutral through July and August and exceeded El Niño thresholds in September. However, this was primarily due to well above-average atmospheric pressure at Darwin. The corresponding pressure in Tahiti was within normal bounds, suggesting the September SOI value was not related to a developing El Niño. Other atmospheric indicators of ENSO (trade winds and cloudiness in the central Pacific) remain at normal levels. All international climate models expect Eastern Pacific Ocean temperatures to remain within neutral levels until February 2020.

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