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

While the SOI is an important index that tracks changes in tropical air pressure, we consider a much wider range of atmospheric and oceanic conditions when we assess the status of ENSO. This includes winds, clouds, ocean currents and both surface and sub-surface ocean temperatures, as well as outlooks for the months ahead.

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 temperatures (SSTs) for the week ending 16 February were close to average across the eastern half of the equatorial Pacific Ocean, but remain warmer than average across the western half. Warm anomalies have decreased slightly in the western Pacific compared to two weeks ago, but overall ocean temperature patterns remain consistent with a neutral ENSO state.

SSTs also remain warmer than average around most of Australia. SSTs are up to two degrees warmer than average across most of the Coral Sea, much of the Tasman Sea, and extend well east New Zealand.

Consistent with the neutral state of the Indian Ocean Dipole, there is little difference in surface temperature between the east and west of the tropical Indian Ocean.

The latest values of the three key NINO indices in the tropical Pacific for the week ending 16 February were: NINO3 +0.1 °C, NINO3.4 +0.3 °C and NINO4 +0.8 °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 El Niño–Southern Oscillation (ENSO) remains neutral. Atmospheric and oceanic indicators including the Southern Oscillation Index (SOI), cloudiness near the Date Line, and sea surface and sub-surface temperatures in the tropical Pacific are at neutral ENSO levels. However, trade winds, another ENSO indicator, are currently weaker than usual near the Date Line. This is a result of warmer waters in that area and tropical cyclone activity in the region. Additionally, some surface waters in the tropics, near and to the west of the Date Line, are warmer than average, potentially drawing some moisture away from Australia. This pattern in the western Pacific is offset by anomalously warm sea surface temperatures around northern Australia, which tend to increase rainfall.

International climate models surveyed by the Bureau suggest that ENSO is likely to stay neutral until at least the end of the southern hemisphere autumn, meaning it will have limited influence on Australian and global climate in the coming months.

The Indian Ocean Dipole (IOD) remains neutral. The IOD typically has little influence on Australian climate from December to April.

The Southern Annular Mode (SAM) is also currently neutral and is forecast to remain neutral for the next three weeks. The SAM has less impact upon Australian rainfall in autumn.

Cloudiness near the Date Line has generally been above average since mid-December. Overall cloud patterns are consistent with neutral ENSO.

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 16 February were weaker than average over the western half of the tropical Pacific, and reversed (i.e. westerly) in some regions. Winds were close to average across the eastern half of the Pacific.

It is likely that tropical cyclones in the region have contributed to the weakened trade winds in the western 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.

Most international climate models indicate central tropical Pacific sea surface temperatures in the NINO3.4 region will remain at ENSO-neutral levels until at least the start of the southern hemisphere winter. One of the eight models exceeds the La Niña threshold during July.

ENSO events, that is either El Niño or La Niña, typically begin to develop during autumn, before strengthening in winter/spring. The Bureau will continue to closely monitor the potential for either to develop this year.

The surface of the ocean remained warmer than average across much of the western equatorial Pacific Ocean during January.

The surface of the ocean was also warmer than average around much of Australia during January.

The January values of the three key NINO indices were: NINO3 +0.3 °C, NINO3.4 +0.5 °C, and NINO4 +0.8 °C.

The 30-day Southern Oscillation Index (SOI) for the 30 days ending 16 February was −1.5. The 90-day value was −3.2.

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 value to 16 February was +0.01 °C.

There is currently little temperature gradient across the Indian Ocean, which is consistent with neutral IOD. Sea surface temperatures remain warmer than average across much of the basin.

The IOD typically has little influence on Australian climate from December to April. When the monsoon trough shifts southwards into the southern hemisphere, it changes the broadscale wind patterns, meaning that the IOD pattern is unable to form.

Presently, one of the six international climate models indicates that a positive IOD may emerge during the southern hemisphere autumn. However, at this time of year the accuracy of IOD forecasts beyond autumn is low.

The four-month sequence of equatorial sub-surface temperature anomalies (to January) shows the top 150 m of the equatorial Pacific is warmer than average between about 160°E and 160°W, reaching more than two degrees warmer than average. Slightly cooler than average waters are present at a depth of around 50 to 150 m across most of the remainder of the equatorial Pacific.

The pattern has remained somewhat similar since November, with mostly weak to moderate temperature anomalies.

For the five days ending 16 February, temperatures were warmer than average around and east of the Date Line between 100 and 150 m depth. Anomalies in this region remain similar to two weeks ago, reaching more than three degrees warmer than average. This warming of the sub-surface may have been a result of a burst of westerly winds associated with the recent Madden-Julian Oscillation event.

Elsewhere in the sub-surface of the equatorial Pacific Ocean, sub-surface temperatures were generally close to average.

Product code: IDCKGEWW00