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) across the central Pacific Ocean remain close to average along the equator.

The latest values for the week ending 22 April are: NINO3 −0.2 °C, NINO3.4 −0.3 °C and NINO4 +0.1 °C. Persistent NINO3 or NINO3.4 values cooler than −0.8 °C typically indicate La Niña, while persistent values warmer than +0.8 °C are typical of El Niño.

Warmer than average SSTs (more than 1 °C above average) persist in areas surrouding New Zealand, including the South Pacific and the Tasman Sea, though surface temperatures in this region have cooled slightly compared to two weeks ago. The surface of the Tasman Sea has been persistently warmer than average since the second half of November 2017. This was a record-breaking marine heatwave event.

To the north of Australia, weak warm SST anomalies remain across the Maritime Continent.

In the tropical Pacific, the El Niño–Southern Oscillation (ENSO) remains neutral—neither El Niño nor La Niña. All climate models indicate the tropical Pacific Ocean will continue to warm slowly, but temperatures will remain close to average through the southern hemisphere winter.   

Most atmospheric and oceanic indicators of ENSO are at neutral levels. Sea surface temperatures in the central Pacific are close to average for this time of year. Beneath the surface, the tropical Pacific Ocean is slightly warmer than average, but well within the neutral range. In the atmosphere, cloud patterns remain La Niña-like, but trade winds are close to average.

All international climate models surveyed by the Bureau suggest that sea surface temperatures in the tropical Pacific will continue to rise, but remain ENSO neutral for the remainder of the southern autumn and winter. By September, two of the eight models suggest ocean temperatures may approach El Niño thresholds.

The Indian Ocean Dipole (IOD) is currently neutral. Most models indicate a neutral IOD is likely for autumn and early winter. However, three of six models indicate a negative IOD is possible during winter. Typically during negative IOD events, winter–spring rainfall is above average over southern Australia.

Climate model outlooks for ENSO and the IOD have lower accuracy during autumn than at other times of the year. Hence current model outlooks for these climate drivers should be viewed with some caution.

Cloudiness near the Date Line has been below average since late February. Broadly, across the central tropical Pacific Ocean, a La Niña-like cloud pattern has persisted.

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 22 April are near average across most of the equatorial Pacific, and weaker than average over a small area of the far western equatorial Pacific.

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.

All eight of the surveyed international climate models indicate equatorial Pacific sea surface temperatures are likely to rise further over the coming months. A neutral ENSO state is the most likely outcome for the remainder of the southern hemisphere autumn and winter.

Two models indicate central Pacific sea surface temperatures may approach El Niño threshold values during spring, however model outlooks produced during or spanning autumn have a lower accuracy than at other times of the year, and should be viewed with some caution.

Sea surface temperature (SST) anomalies for March show SSTs were slightly cooler than average in the central and eastern tropical Pacific Ocean. Warm anomalies were present across most of the South Pacific around and south of 30°S, the northern Maritime Continent, to the west of Japan and to the east of Mexico.

The March value for NINO3 was −0.6 °C, NINO3.4 −0.6 °C, and NINO4 0.0 °C.

The 30-day Southern Oscillation Index (SOI) to 22 April was +9.5, while the 90-day SOI remains within the neutral range at +4.4.

With the northern Australian monsoon season now over, fluctuation of the SOI associated with the movement of tropical weather systems is expected to decrease.

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

The Indian Ocean Dipole (IOD) is currently neutral. The weekly index value to 22 April was −0.03 °C.

Three of the six international climate models surveyed by the Bureau anticipate that the IOD will become negative IOD during the southern hemisphere winter. A negative IOD during winter tends to enhance rainfall across southern Australia.

It should be noted that outlook skill is lower at this time of year.

The four-month sequence of sub-surface temperature anomalies (to 19 April) shows that the central and eastern equatorial Pacific Ocean has slowly warmed over the past three months. A pool of warmer than average water is present between 140°E and 140°W across the top 200 m of the Pacific, with cool anomalies in the shallow sub-surface of the eastern equatorial Pacific. Eastward propagation of warm sub-surface anomalies, as seen in recent months, is a typical feature of a decaying La Niña.

Sub-surface temperatures for the 5 days ending 22 April show a pool of slightly warmer than average water persists in the top 200 m of the equatorial Pacific, extending across most of the equatorial Pacific. Temperatures in the top 50 m and below 200 m depth are near average for this time of the year.

Product code: IDCKGEWW00