South Pacific tropical cyclone season outlook

Australian outlook

2014–15 South Pacific Tropical Cyclone Outlook

Near average tropical cyclone season likely for the South Pacific

Chance of above average tropical cyclone activity

Region Outlook summary
(near, below or above
Chance of
above average
Long-term average
number of tropical cyclones*
South Pacific Near average 55% 14
Western Below average 39% 7
Eastern Near average 55% 10

*The long-term average number of tropical cyclones may change slightly from one year to the next as a new season of data is added to the calculation. The average number of tropical cyclones for the western and eastern region add to more than the average for the South Pacific, as cyclones that develop in one region and cross the border are counted twice when averages are added.

This outlook is based upon the status of the El Niño—Southern Oscillation (ENSO) over the preceding July to September period. Whilst the Pacific Ocean has remained neutral during these months, ocean temperatures have been near El Niño thresholds. The Southern Oscillation Index, the measure of the atmospheric component of ENSO, has been negative through this period. Climate models suggest there is still double the normal chance of El Niño occurring this summer (i.e. 50% chance). During an El Niño, tropical cyclone numbers in the Western Region of the South Pacific tend to be below average.

The model has a good level of accuracy predicting cyclone numbers in the western region, a very low level of accuracy for the eastern region and a low level of accuracy for the South Pacific region.

Past South Pacific tropical cyclone season outlooks

About the outlooks

This outlook is produced using statistical relationships between tropical cyclone numbers and two indicators: the Southern Oscillation Index (SOI) and the Niño3.4 sea surface temperature index (NINO3.4 SST). These indicators provide a measure of the strength of the atmospheric and oceanic state, respectively.

The July, August and September SOI and NINO3.4 values were used in making the South Pacific tropical cyclone season outlook.

2013 July August September
SOI +8.1 -0.5 3.9
NINO3.4 SST -0.31°C -0.28°C -0.03°C

The current status of ENSO can be viewed via the Bureau's ENSO Wrap-up. Tropical Pacific Ocean temperatures have been in a neutral state since October 2012. This means that the sea surface temperature patterns in the Pacific are neither La Niña nor El Niño and is therefore not driving the South Pacific region toward significantly more or fewer tropical cyclones than average. As such, the forecast is suggesting a season closer to average.

Further information