ENSO Wrap-Up
Current state of the Pacific and Indian oceans


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

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ENSO outlooks

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.

Indian Ocean Dipole outlooks

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.

Sea surface temperature (SST) anomalies for the week ending 14 April are warmer than average across most of the tropical Pacific Ocean. Compared to two weeks ago, the surface of the ocean has cooled slightly in the west. 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 half of the Pacific Ocean. In particular, the area to the east of Australia and surrounding New Zealand is broadly up to 2 °C warmer than average. Waters around the rest of Australia are closer to average, but the Great Australia Bight is also warmer than average. 

The latest values of the three key NINO indices in the tropical Pacific for the week ending 14 April are: NINO3 +0.7 °C, NINO3.4 +0.8 °C and NINO4 +0.6 °C. The ocean surface in the western region (NINO4) has cooled slightly compared to two weeks ago, while the other regions remain steady.

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 Bureau's ENSO Outlook remains at El Niño ALERT. This means the chance of El Niño developing in the coming months is approximately 70%; around triple the normal likelihood.

Although sea surface temperatures in the tropical Pacific Ocean are still close to El Niño thresholds, the atmosphere is yet to show a consistent El Niño-like response. The Southern Oscillation Index, which typically drops when an El Niño pressure pattern develops across the equatorial Pacific, remains neutral and trade winds are currently close to normal strength near the equator.

While climate models forecast El Niño-like ocean temperatures during May, most models indicate a cooling through winter, with only three of eight models still forecasting El Niño-like warmth in spring. This indicates that if El Niño does develop it is likely to be short lived and weak.

El Niño typically brings drier than average conditions for eastern Australia during winter–spring, and warmer days across southern Australia. During the autumn months, the influence of El Niño tends to be weaker, but can bring drier conditions to the south of the country.

In the Indian Ocean, most climate models indicate the Indian Ocean Dipole (IOD) is likely to be neutral for the remainder of the austral autumn, with the possibility of a positive IOD in winter or spring. A positive IOD typically means drier than average conditions for southern and central Australia during winter-spring.

Cloudiness near the Date Line has been above average since early December, however, it has been closer to average in recent weeks. 

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 14 April are close to average. 

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 throughout the remainder of the austral autumn and early winter, the ocean is then likely to cool heading into spring, with only three of the eight surveyed climate models still forecasting El Niño-like warmth in spring. This could indicate that if El Niño does develop, it is likely to be short lived and weak. 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 after May.

Sea surface temperatures (SSTs) for March were warmer than average across the equator in the Pacific Ocean. Much of the equatorial region is warmer when compared to February. 

A significant area of warmer than average SSTs exists to the east of Australia, and surrounding New Zealand; temperatures are up to 2 °C above average in this region. The Great Australian Bight is also warmer than average, as well as areas off the northwest coast of Australia. SSTs are closer to average along the Queensland coastline and the southern half of the WA west coast. 

The March values for NINO3 were +0.7 °C, NINO3.4 +0.8 °C, and NINO4 +0.8 °C, with both the central and eastern regions warming compared to February. 

The 30-day Southern Oscillation Index (SOI) has eased back to more neutral levels over the past fortnight. The SOI for the 30 days ending 14 April was −2.0, with the 90-day average −5.8.

As the northern Australian wet season nears it end, the SOI will become less volatile, and will be expected to better reflect the climatic conditions. During the wet season, the passage of tropical systems near Darwin and Tahiti can affect atmospheric pressure at these locations, meaning that SOI values during the northern Australian wet season can be erratic, and should therefore be viewed with caution.

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 14 April is −0.04 °C.

All of the six international climate models surveyed by the Bureau indicate that the IOD will be neutral for May. By July, one model indicates a positive IOD may form, with three of six models predicting a positive IOD may be possible in spring.

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

The four-month sequence of equatorial sub-surface temperature anomalies (to March) shows that although the sub-surface of the tropical Pacific has cooled, positive anomalies persist across most of the top 125 m of the sub-surface. A small volume of negative anomalies has developed between roughly 125 m and 200 m depth around the Date Line, between 170°W and 150°E.

The sub-surface of the ocean for the five days ending 14 April was slightly warmer than average across the shallow sub-surface, with the top 100 m of the equatorial Pacific more than 1 °C warmer than average. However, the ocean sub-surface has been slowly cooling over the past several weeks.

Product code: IDCKGEWW00