Climate Model Summary

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.

Models indicate increased chance of negative IOD, as La Niña looks to ease over winter

The 2021–22 La Niña continues to weaken with latest observations and outlooks indicating a return to neutral-ENSO by July. All but one of the surveyed models predict neutral, but cooler than average, temperatures in the central tropical Pacific throughout the southern winter. During spring however, the model outlooks show a broader spread in outcomes, with three models indicating a return to La Niña values and four models maintaining neutral-ENSO values. Despite La Niña easing, it's likely that ocean temperature patterns in the Pacific will still contribute to a wetter than average winter across eastern Australia. Model accuracy at this time of year is moderate to high.

The Indian Ocean Dipole (IOD) is neutral but index values have been close to the negative IOD threshold for the last five weeks. All model outlooks indicate a negative IOD event is likely to develop in the coming weeks. A negative IOD event can enhance winter and spring rainfall across much of Australia, as well as influencing rainfall patterns in countries around the Indian Ocean basin. Outlook accuracy is typically low during autumn but increases during the winter months. The consistent outlook for a negative IOD across all the surveyed models provides additional confidence in the outlook. 

NINO3.4 outlook

The latest weekly NINO3.4 value to 12 June 2022 is −0.4 °C, falling well short of the La Niña threshold (−0.8 °C) and suggesting an easing of La Nina. All but one of the seven surveyed models predict neutral, but cooler than average, temperatures in the central tropical Pacific throughout the southern winter.

During spring however, the model outlooks show a broader spread in outcomes, with one model indicating a return to La Niña values from late winter and two additional models touching on La Niña thresholds from mid-spring. The remaining four models maintain neutral-ENSO values. Despite La Niña easing, it is likely that ocean temperature patterns in the Pacific will still contribute to a wetter than average winter across eastern Australia. Model accuracy at this time of year is moderate to high.

La Niña typically increases the chances of above average rainfall for much of eastern Australia during winter and spring. It is not uncommon to experience some La Niña-like conditions when values are close to La Niña thresholds.

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

The IOD remains neutral, but the weekly IOD index briefly dipped below negative IOD thresholds in recent weeks. It is currently just shy of the threshold, recording −0.37 °C for the week ending 12 June 2022. All models surveyed indicate a negative IOD event could develop in the coming weeks, with several forecasting strong negative index values developing by August. A negative IOD increases the chance of above average winter-spring rainfall across much of Australia.

Outlook accuracy is typically low during autumn but increases during the winter months. The consistent outlook for a negative IOD across all the surveyed models provides additional confidence in the outlook. 

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 4 June 2022) indicates sea surface temperature in the central tropical Pacific (NINO3.4) are likely to warm to within the neutral ENSO range in June and remain neutral through to at least the start of the southern spring. Model skill is generally moderate to high at this time of year.

The current outlook for the Indian Ocean Dipole (IOD) indicates IOD index values are likely to continue to drop during winter, with strong negative values developing by July. Model accuracy for IOD outlooks at this time of year is relatively low but steadily improves during winter. A negative IOD event typically enhances winter and spring rainfall across much of Australia.

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

Product code: IDCKGL0000

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