Climate Driver Update Archive
Climate drivers in the Pacific, Indian and Southern oceans and the Tropics


Average of international model outlooks for NINO3.4

Average of international model outlooks for IOD


Sea surface temperature maps

Sea surface temperature maps are not available for forecasts before Spring 2018

Global sea surface temperature outlooks for the months and season ahead. Anomalies indicate the difference from normal.

Sea surface temperature maps (select map for larger view)

SST outlooks for the next 3 months

Pacific Ocean

ENSO is the oscillation between El Niño and La Niña states in the Pacific region. El Niños typically produce drier seasons, and La Niñas drive wetter years, but the influence of each event varies, particularly in conjunction with other climate influences.

NINO3.4 SST plumes from Bureau model forecasts, updated daily
Select to see full-size map of NINIO3.4 SST plumes from Bureau model forecasts, updated daily.

International climate model outlooks

Nino 3.4 2 month outlook
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.

Weekly sea surface temperatures

Graphs of the table values

Monthly sea surface temperatures

Graphs of the table values

5-day sub-surface temperatures

Monthly temperatures

Southern Oscillation Index

30-day SOI values for the past two years
Select to see full-size map of 30-day Southern Oscillation Index values for the past two years, updated daily.

Trade winds

5-day SST and wind anomaly from TAO/TRITON
Select to see full-size map of 5-day SST and wind anomaly from TAO/TRITON.

Cloudiness near the Date Line

The Indian Ocean Dipole (IOD) compares sea surface temperatures. An IOD negative state, having warmer than average sea surface temperatures near Australia, provides more moisture for frontal systems and lows crossing Australia.

IOD SST plumes from Bureau model forecasts, updated daily
Select to see full-size map of IOD SST plumes from Bureau model forecasts, updated daily.

International models

Latest IOD outlook
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.

The Southern Annular Mode, or SAM, refers to the north-south shift of rain-bearing westerly winds and weather systems in the Southern Ocean compared to the usual position.

The Madden-Julian Oscillation (MJO) is the major fluctuation in tropical weather on weekly to monthly timescales. It can be characterised as an eastward moving 'pulse' of cloud and rainfall near the equator that typically recurs every 30 to 60 days.

Sea surface temperature (SST) anomalies for the week ending 27 May were warmer than average across nearly the entire tropical Pacific Ocean. Compared to two weeks ago, the surface of the central tropical Pacific Ocean has warmed slightly, in response to recent Madden-Julian Oscillation activity and associated weakening of the trade winds. Most of the tropical Pacific region is half to one degree warmer than average.

Waters are also warmer than average across much of the southern Pacific Ocean, particularly across areas south of 30°S. SSTs are up to two degrees warmer than average over a broad area extending across the Tasman Sea, along the New South Wales coast, and well to the east of New Zealand. Waters around the rest of Australia are generally close to average temperatures, although weak cool anomalies are present to the southwest of Australia and in the west of the Great Australian Bight.

The latest values of the three key NINO indices in the tropical Pacific for the week ending 27 May are: NINO3 +0.7 °C, NINO3.4 +0.8 °C and NINO4 +0.7 °C.

Persistent NINO3 or NINO3.4 values warmer than +0.8 °C are typical of El Niño, while persistent values cooler than −0.8 °C typically indicate La Niña.

The Pacific Ocean and overlying atmosphere remain close to El Niño thresholds, so the ENSO Outlook remains at El Niño WATCH. Models indicate the tropical Pacific Ocean will ease away from El Niño levels, becoming neutral during winter. The Indian Ocean is expected to become the dominant influence on Australian climate, with models predicting a positive phase of the Indian Ocean Dipole (IOD) is likely to develop in the coming months.

An active phase of the Madden-Julian Oscillation in the last fortnight weakened the trade winds and brought a small rise in sea surface temperatures (SSTs) in the central and western tropical Pacific Ocean and a drop in the Southern Oscillation Index (SOI). This has sustained the El Niño-like pattern in the Pacific. While a prolonged weakening of the trade winds could elevate El Niño chances once again, the majority of surveyed models suggest the tropical Pacific will cool to neutral levels during winter.

In the Indian Ocean, further warming off the horn of Africa has meant that the IOD index exceeded the positive threshold value this week. All but one of the models surveyed suggest positive IOD levels will be maintained throughout winter. To be considered an event, these values would need to be sustained for at least two months. A positive IOD often results in below average winter–spring rainfall over southern and central Australia.

Cloudiness near the Date Line has been generally above average since early December, however, values have fluctuated closer to average since late April.

Equatorial cloudiness near the Date Line typically increases during El Niño (negative OLR anomalies) and decreases during La Niña (positive OLR anomalies).

Trade winds for the 5 days ending 26 May are weaker than average across most of the western half of the tropical Pacific, likely tied in with recent stalling of Madden-Julian Oscillation activity over the western hemisphere and Africa. Persistent weaker trade winds could lead to further warming of parts of the tropical Pacific Ocean, and raise the odds of El Niño once again. 

Trade winds are close to average across the eastern half of the tropical Pacific.

During El Niño there is a sustained weakening, or even reversal, of the trade winds across much of the tropical Pacific. Conversely, during La Niña, there is a sustained strengthening of the trade winds.

While most climate models forecast El Niño-like warmth to persist into June, the ocean is forecast to cool over winter and into early spring.

While six of the eight surveyed climate models anticipate El Niño thresholds will be met for June, for August and September only two models remain above the El Niño threshold and a third is close to borderline values. By October just two models forecast El Niño, with the remaining six models indicating neutral conditions are most likely.

Note that model accuracy when forecasting through the autumn months is lower than at other times of the year, due to the natural cycle of ENSO. Forecast accuracy improves for outlooks issued in June.

Sea surface temperatures (SSTs) for April were warmer than average across most of the tropical Pacific Ocean. Temperature anomalies in many areas had decreased slightly compared to March.

A significant area of warmer than average SSTs were present surrounding southeast Australia, extending across the Tasman Sea and well to the east of New Zealand; temperatures were up to two degrees warmer than average in much of this region. Waters were also warmer than average in coastal waters of much of the Great Australian Bight, while areas of cool anomalies were present to the southwest of Australia.

The March values for NINO3 were +0.7 °C, NINO3.4 +0.7 °C, and NINO4 +0.6 °C, with values for both the central and western regions cooler than for March.

The 30-day Southern Oscillation Index (SOI) remains neutral. The SOI value for the 30 days to 26 May was −7.4, while the 90-day average has risen to −5.3.

Sustained negative values of the SOI below −7 typically indicate El Niño while sustained positive values above +7 typically indicate La Niña. Values between +7 and −7 generally indicate neutral conditions.

The Indian Ocean Dipole (IOD) is currently neutral. The latest weekly index value to 26 May is +0.53 °C. This is the first week the index value has risen above the threshold value for a positive IOD event. For an event to be considered to have occurred, the IOD value needs to be above the threshold value for at least eight weeks.

The current positive IOD value is being driven by warmer than average sea surface temperatures across most of the Indian Ocean basin, and closer to average temperatures in parts of the eastern node of the IOD, near the Indonesian island of Sumatra.

All six of the international climate models surveyed by the Bureau indicate that the IOD will remain positive during June. For July, one model drops back to neutral, but the other five models forecast positive IOD values to persist through to at least the end of the outlook period (October).

A positive IOD often results in below average winter–spring rainfall over southern and central Australia.

The four-month sequence of equatorial sub-surface temperature anomalies (to 23 May) shows a similar pattern of sub-surface anomalies for May to those for April, although anomalies are generally weaker this month than last.

Very weak positive anomalies persist across most of the top 100 m of the sub-surface, with most of this region with half a degree of average. Below 100 m depth, weak cool anomalies also persist, with some parts of the sub-surface up to two degrees cooler than average.

Temperatures for the five days ending 27 May show waters were very slightly warmer than average in the shallow sub-surface of the eastern equatorial Pacific, with waters in a small region of the top 50 m around 120°W more than two degrees warmer than average. Compared to two weeks ago, warm anomalies in this area have continued to reduce.

Elsewhere temperatures were close to average.

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