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

Indian Ocean Dipole outlooks

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

Sea surface temperatures (SSTs) in the central tropical Pacific Ocean are within the ENSO-neutral range, but remain slightly cooler than average along most of the central equatorial Pacific. Cool anomalies to the immediate east of the Date Line have weakened over the past two weeks but have strengthened slightly along the remainder of the equator in the central and eastern Pacific.

SSTs in the western Pacific and across South East Asia, including areas around northern Australia and across the Tasman Sea, remain warmer than average, but warm anomalies have weakened compared to two weeks ago.

Warm SST anomalies also persist in the eastern Indian Ocean between northwest Australia and Indonesia. Cool anomalies have largely disappeared from the western Indian Ocean. Area of water between the south of Indonesia and northwestern Australia remain at least 1 °C warmer than average, with some areas more than 2 °C above average. While the decline of cool anomalies in the west is consistent with a breakdown of the Indian Ocean Dipole (IOD) pattern, very warm waters in the east mean that the negative IOD event, and potential Australian impacts, continues.

The tropical Pacific Ocean remains El Niño–Southern Oscillation (ENSO) neutral. Negative Indian Ocean Dipole (IOD) conditions continue, but are likely to ease by the end of spring.

Trade winds in the tropical Pacific have returned to near-average after a surge in early October. Correspondingly, sea surface temperatures (SSTs) in the central tropical Pacific Ocean cooled, but then rebounded, and remain within the ENSO neutral range. In the atmosphere, the Southern Oscillation Index (SOI) has returned to near-zero values. However, cloudiness near the Date Line continues to reflect a La Niña-like pattern.

Most climate models predict SSTs will remain cooler than average, but ENSO-neutral, through until the end of the 2016–17 summer. Only two of eight models suggest brief, weak La Niña levels may occur towards the end of 2016. The ENSO Outlook remains at La Niña WATCH.

Warmer than average sea surface temperatures to Australia's north suggest that some La Niña-like impacts are likely, even if an event never fully develops.

The negative IOD event, which has been in place since late May, persists. Warming of SSTs east of tropical Africa has seen IOD index values weaken over the past month, but SSTs remain very much warmer than average south of Indonesia. Models indicate the IOD will return to neutral by the end of spring. Both a negative IOD and La Niña typically contribute to increased rainfall in spring for eastern and central Australia.

Cloudiness near the Date Line is below average, and has been generally below average since the start of August.

Equatorial cloudiness near the Date Line typically increases during El Niño (below average OLR) and decreases during La Niña (above average OLR).

Trade winds for the 5 days ending 23 October across the tropical Pacific Ocean were generally close to average strength, and very slightly stronger than average in the far western tropical Pacific (west of 170° E).

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

Outlooks from the eight international climate models surveyed by the Bureau continue to indicate that neutral ENSO conditions are the most likely outcome for the southern hemisphere spring–summer period. However, two models indicate the likelihood of a brief, late-starting La Niña over the summer.

If La Niña does form, models suggest it will be weak, potentially short-lived, and well below the strength of the significant 2010–12 event.

Weak cool SST anomalies persisted in a small region of the equatorial central Pacific during September. Warm anomalies have replaced cool anomalies along the equator in the eastern Pacific since August. September SSTs were warmer than average both north and south of the equator across most of the tropical Pacific, and across a large area of the tropical to temperate western Pacific south of the equator. Waters are also warmer than average around Australia, Indonesia and South East Asia. Large areas adjacent to southeast Australia and between Australia and Indonesia were more than 1 °C warmer than average.

The September value for the NINO3 region was −0.1 °C, 0.2 °C warmer than for August, while the value for the NINO3.4 region remained unchanged at −0.4 °C, and NINO4 was 0.2 °C cooler 0.0 °C. The eastern node of the IOD was second-warmest on record for September in the ERSSTv4 dataset.

The latest 30-day Southern Oscillation Index (SOI) to 23 October is +2.6; within the neutral ENSO range. SOI values have been within the neutral range for the past week following a spike to values around +13 during the previous month.

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

The negative Indian Ocean Dipole (IOD) event continues. Index values remain well below their peak earlier in winter, although have increased in strength over the past fortnight. The weekly index value to 23 October was −0.56 °C.

International climate models indicate the negative IOD will steadily weaken during spring, as is typical of the lifecycle of IOD events. The influence of the IOD on Australian climate is weak during the months December to May as the
monsoon trough shifts south over the tropical Indian Ocean.

A negative IOD typically brings above average rainfall to eastern Australia during spring, cooler than normal daytime temperatures to southern Australia, and warmer daytime and night-time temperatures to northern Australia.

The four-month sequence of sub-surface temperature anomalies (to 20 October) shows cool anomalies span the entire width of the equatorial Pacific Ocean. Cool anomalies below about 100 m depth to the west of the Date Line have cooled slightly each month since August. Weak warm anomalies persist in the top 100 m of water west of 170° W; water in this region has been slightly warmer than average in each month since July.

The sub-surface temperature map for the 5 days ending 23 October shows temperatures generally close to average across the sub-surface of the equatorial Pacific. A very small area of moderately strong cool anomalies was present around 100 m depth at 140° W, reaching more than 4 degrees cooler than average.

Product code: IDCKGEWW00