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 24 November remain warmer than average across most of the equatorial Pacific Ocean. Compared to two weeks ago, warm anomalies in the western Pacific have increased. Overall, patterns are consistent with a neutral ENSO state.

Weak cool anomalies persist in some parts of the Coral Sea and on the southern side of the Indonesian archipelago, but have decreased in strength compared to two weeks ago, in line with continued weakening of the positive IOD. SSTs are mostly within 2 degrees of average in areas close to Sumatra. Warm anomalies persist off the Horn of Africa, and remain similar to two weeks ago, reaching between 1 and 2 degrees warmer than average.

The latest values of the three key NINO indices in the tropical Pacific for the week ending 24 November are: NINO3 +0.5 °C, NINO3.4 +0.6 °C and NINO4 +0.9 °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.

In the tropical Pacific Ocean, the El Niño–Southern Oscillation (ENSO) remains neutral, while in the Indian Ocean the strong positive Indian Ocean Dipole (IOD) event continues.

IOD values remain strongly positive but have weakened slightly over the past fortnight. Waters are warmer than average near the Horn of Africa, and cooler than average waters persist in the eastern Indian Ocean, south of Indonesia. International climate models surveyed by the Bureau indicate the positive IOD is likely to be slower to decline than usual, and may persist into mid-summer.

Typically, a positive IOD brings below average rainfall to southern and central Australia with warmer days for the southern two-thirds of the country. Positive IOD events are often associated with a more severe fire season for southeast Australia.

In the tropical Pacific Ocean, the El Niño–Southern Oscillation (ENSO) remains neutral. While tropical Pacific Ocean sea surface temperatures are slightly warmer than average, atmospheric indicators are generally neutral. Trade winds have recently weakened temporarily in the western Pacific region in line with severe tropical cyclone Rita. This may mean there is some warming of surface waters in the coming few weeks. However, most climate models forecast ENSO-neutral conditions for the rest of 2019 and into the first quarter of 2020. When ENSO is neutral, it has little effect on Australian and global climate, meaning other influences are more likely to dominate.

Cloudiness near the Date Line has generally remained below average since early to mid-September. Overall cloud patterns are consistent with neutral ENSO.

OLR data for the most recent 5 days is not yet available due to a technical outage. It is possible that severe tropical cyclone Rita, near Vanuatu, may have brought an increase in cloudiness in the surrounding region.

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

Cloudiness in the eastern tropical Indian Ocean has been well below average, while cloudiness is well above average in the western Indian Ocean. This indicates a mature and strong positive Indian Ocean Dipole.

Trade winds for the 5 days ending 24 November were close to average across the central and eastern tropical Pacific, and weaker than average in the west. This weakening of trade winds in the west is likely associated with tropical cyclone Rita. Weakened trade winds in the west currently may result in warming of surface waters in the region in coming weeks.

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.

In the Indian Ocean, trade winds have generally been much stronger than average over the past few months, typical of a strong positive IOD phase.

All eight surveyed international climate models indicate central tropical Pacific sea surface temperatures in the NINO3.4 region will remain at ENSO-neutral levels into early 2020.

One model indicates that values may move towards La Niña thresholds over autumn, surpassing the threshold value during April. The remaining models all maintain NINO3.4 values within the neutral range throughout the outlook period.

Sea surface temperatures (SSTs) for October were warmer than average across much of the equatorial Pacific Ocean, and cooler than average in some parts of the eastern tropical Pacific close to South America.

SSTs were warmer than average in areas around southeastern Australia and much of western Australia. SSTs were mostly close to average around the rest of Australia, though there were cool anomalies in some areas to the north of Australia.

The October values for NINO3 were +0.3 °C, NINO3.4 +0.6 °C, and NINO4 +1.0 °C. All three NINO indices warmed compared to September.

The 30-day Southern Oscillation Index (SOI) for the 30 days ending 24 November was −10.5. The 90-day value was −9.7. The 30-day SOI values have remained fairly similar over the past week, and are more strongly negative than they were two weeks ago.

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) remains strongly positive, although IOD index values have decreased compared to values in October. The latest weekly value to 24 November was +1.36 °C.

The strong temperature gradient persists across the Indian Ocean. SSTs to the south of the Indonesian islands of Sumatra are up to 2 degrees cooler than average for the week ending 24 November, while warm anomalies in the west of the Indian Ocean near the Horn of Africa are up to 2 degrees warmer than average. The overall pattern of sea surface temperatures has remained generally consistent with a positive IOD pattern since late May.

All six international climate models surveyed by the Bureau indicate the IOD will remain positive into December, with five of the six models indicating persistence into January.

While the IOD continues to show signs it will persisted later than usual this year, it remains unlikely that the positive IOD will persist into the second half of summer. IOD events dissipate as the monsoon trough moves into the southern hemisphere, which changes the broadscale wind patterns over the IOD region and returns sea surface temperatures to near average.

The four-month sequence of equatorial sub-surface temperature anomalies (to 21 November) shows cool anomalies in the western to central equatorial Pacific, at a depth of around 100 to 200 m. Weak warm anomalies extend across most of the top 100 m of the equatorial Pacific.

Warm anomalies in the central Pacific intensified in October, compared to September and August, but have decreased for November to date. Cool anomalies extend further east now than they did for October.

For the five days ending 24 November water temperatures were close to average across much of the sub-surface of the equatorial Pacific, with areas of the top 100 m somewhat warmer than average in both the west and east of the equatorial Pacific. In the eastern equatorial Pacific part of the top 100 m is more than 3 degrees warmer than average for this time of year.

Product code: IDCKGEWW00