Climate Model Summary

Negative IOD likely to continue through spring; models suggest La Niña may return later in 2022

A negative Indian Ocean Dipole (IOD) event is underway. All model outlooks indicate that negative IOD conditions are likely to continue into late spring. A negative IOD event increases the chances of above average winter and spring rainfall across much of Australia, as well as influencing rainfall patterns in countries around the Indian Ocean basin.

While the 2021–22 La Niña has ended, a La Niña WATCH remains, meaning there is around a 50% chance of a La Niña event returning later in 2022. Most models predict neutral conditions until the end of August. However, by October four of seven models indicate the tropical Pacific Ocean will cool again to La Niña levels. It is likely that ocean temperature patterns in the Pacific will still contribute to wetter than average conditions across eastern Australia, even if La Niña thresholds are not reached.

NINO3.4 outlook

The latest weekly NINO3.4 value to 31 July 2022 is −0.4 °C, remaining neutral. A La Niña WATCH is been active, meaning there is around a 50% chance of La Niña returning later in 2022.

Five of seven surveyed models predict neutral but cooler than average temperatures in the central tropical Pacific to persist through to the end of August, while two show cooling back to La Niña thresholds (−0.8 °C). By October, four of seven models reach La Niña levels. The remaining three models maintain a neutral, though cooler than average, outlook. Despite recent warming in the central tropical Pacific, residual ocean temperature patterns across the Pacific Ocean may still contribute to a wetter than average winter and spring across eastern Australia.

Persistent NINO3.4 values above +0.8 °C typically indicate El Niño, while values below −0.8 °C typically indicate La Niña.

Indian Ocean Dipole (IOD) outlook

A negative Indian Ocean Dipole event is underway. The latest IOD index value for the week ending 31 July is −0.9 °C, below the −0.4 °C threshold. All models surveyed indicate a negative IOD event is likely to persist until late spring. A negative IOD increases the chance of above average winter and spring rainfall across much of Australia.

 

Australian Community Climate Earth-System Simulator–Seasonal (ACCESS–S)

The Bureau of Meteorology's climate model generates a six-month forecast for the NINO and IOD indices each fortnight.

The most recent model run (generated 30 July 2022) indicates sea surface temperature in the central tropical Pacific (NINO3.4) are likely to remain ENSO-neutral though cooler than average through to the end of the year. 

The latest outlook for the Indian Ocean Dipole (IOD) indicates IOD index values are likely to remain at negative thresholds through the remainder of winter and spring, before returning to neutral values towards the end of 2022. 

The forecast values, shown below in bold, are for the model's ensemble mean.

Product code: IDCKGL0000

Australian climate is influenced by temperature patterns in the Pacific and Indian Oceans. This page provides information on Pacific and Indian Ocean outlooks for the coming six months based on a survey of international climate models.

Further details: Climate Driver Update | Climate Outlooks

Average of international model outlooks for NINO3.4

Average of international model outlooks for the Indian Ocean Dipole (IOD)

Based on the ensemble mean for the most recent model run.

The arrows on the dials indicate the combined average of monthly outlooks from a survey of international global climate models. Note that the individual model runs vary around the average.

 

NINO3.4 covers the central Pacific region.

Graphs

Nino 3.4 2 month outlook Models information
Graph details

The graphs are based on the ensemble mean for the most recent model run.

These graphs show the average forecast value of NINO3.4 for each international model surveyed for the selected calendar month. If the bars on the graph are approaching or exceeding the blue dashed line, there is an increased risk of La Niña. Similarly, if the bars on the graph are approaching or exceeding the red dashed line, there is an increased chance of El Niño.

Graphs

Latest IOD outlook Models information
Graph details

The graphs are based on the ensemble mean for the most recent model run.

Thse graphs show the average forecast value of the IOD index for each international model surveyed for the selected calendar month. If the majority of models are approaching or exceeding the blue dashed line, then there is an increased risk of a negative IOD event. If the majority of models are approaching or exceeding the red dashed line, then there is an increased risk of a positive IOD event.

More information:

Sea surface temperature graphs

Australian climate is influenced by sea surface temperature patterns in the Pacific and Indian oceans. Specific regions are monitored, as they can indicate the presence, or potential development, of ENSO (El Niño/La Niña) and Indian Ocean Dipole (IOD) events.

Sea surface temperature graphs

NINO34 predictions for the next 5 months.

Outlook graph for selected SST region

NINO34 probabilities

About the graphs

The plume graphs show outlook scenarios for sea surface temperatures (SSTs) averaged over particular regions of the Pacific and Indian oceans. The SSTs in these regions are related to different phases of the El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD); climate drivers that can influence Australian rainfall and temperature patterns.

The graphs show 99 possible scenarios (grey lines), that are produced by the Bureau's climate outlook model, which represent the range of outcomes that may occur over the forecast period. For example, they may show the SSTs in the NINO3.4 region to be warming, cooling, or remaining mostly steady. At times the outlook might suggest a shift towards (or away from) values typically associated with El Niño or La Niña events. Each of the 99 scenarios is based on current conditions in the global oceans/atmosphere and how the model anticipates their likely development over the outlook period, with each given slightly different treatment to provide a range of likely possibilities. This technique allows us to see the range of what is possible, with a small spread in the range of scenarios meaning more confidence in the likely path, and a larger spread meaning less confidence.

The green line is the average of all these 99 scenarios, often known as the ensemble mean. The solid black line shows the observations (based on the Bureau's SST observation analysis for each region) for the previous months.

The graphs are updated fortnightly. As a result, the value given for the 'current month' can vary depending on at what point in the month the forecast is being issued. Forecasts made on the 1st to the 11th of the month show a forecast value for the current month. For forecasts made after the 11th of the month, a month-to-date observation (shown by an open circle and dashed line), based on weekly observational data, will be used for the current month as a preliminary value until the final monthly data is available.

These plume graphs and data are also included in the Bureau's Climate Driver Update and Model Summary webpages.

About the maps

While the climate model runs a set of 99 possible scenarios, it can be useful to look at the ensemble mean (the average of these forecasts) to see the most likely scenario. The global SST maps show the most likely SST anomaly for the months and seasons ahead. This can be useful to see how ENSO and IOD look spatially. The SST anomalies show the difference from the 1990-2012 average (often referred to as the base period).

About the outlook model

The long-range SST outlooks are generated by the Bureau's climate model, ACCESS–S (Australian Community Climate Earth-System Simulator–Seasonal). ACCESS–S is the Bureau of Meteorology's dynamical (physics-based) weather and climate model used for monthly, seasonal and longer-lead climate outlooks. Prior to August 2018, climate outlooks (including these graphs) were produced by the Bureau's earlier model, POAMA.

Definitions



Product code: IDCK000073

Model details

The models used within our survey are listed below with links to their agency homepages, model output and technical information about the model.

Model data are provided for Bureau of Meteorology use by the agencies detailed in the Models section. Respective agency copyright applies to these data.

Creative Commons By Attribution logo Unless otherwise noted, all maps, graphs and diagrams in this page are licensed under the Creative Commons Attribution 4.0 International Licence