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

Following links open in new window

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) are close to average in the eastern half of the tropical Pacific Ocean, and slightly above average in the western half, consistent with the current neutral state of ENSO. Waters in the central to eastern region have cooled compared to two weeks ago.

The latest values of the key NINO indices in the tropical Pacific for the week ending 12 August are: NINO3 0.0 °C, NINO3.4 +0.2 °C and NINO4 +0.6 °C. NINO3 and NINO3.4 have cooled compared to two weeks ago, while NINO4 has warmed.

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.

Around Australia, SSTs are generally near average, but weak warm SST anomalies exist around the eastern coastline. Cooler waters can be seen to the northwest of Australia, close to the eastern pole of the Indian Ocean Dipole.

The El Niño–Southern Oscillation (ENSO) is currently neutral. While the tropical Pacific Ocean has cooled in the past month, most international climate models forecast warming to resume in the coming weeks, with El Niño development possible in the southern spring. Therefore, the Bureau's ENSO Outlook remains at El Niño WATCH. El Niño WATCH means there is approximately a 50% chance of El Niño forming in 2018; double the normal chance.

While the surface of the central to eastern tropical Pacific has cooled over the past month, the water below the surface of the western Pacific is warming again. Although atmospheric indicators such as the Southern Oscillation Index (SOI) remain neutral, tropical cyclones to the north of the equator are acting to increase the warmth in the Pacific by suppressing trade winds.

Most international climate models surveyed by the Bureau predict warming of the tropical Pacific is likely to recommence in the coming weeks. Most models suggest El Niño thresholds are likely to be reached by the end of the year, with the majority suggesting these thresholds could be met by mid to late spring.

El Niño during spring typically means below average rainfall in eastern and northern Australia while daytime temperatures are typically above average over southern Australia.

The Indian Ocean Dipole (IOD) is neutral. However, the ocean to the northwest of Australia remains cooler than normal, which is contributing to suppressed rainfall over southern and southeast Australia. Three of six international climate models suggest a short-lived positive IOD event may develop. A positive IOD during spring typically reduces rainfall in central and southern Australia, and can exacerbate any El Niño driven rainfall deficiencies.

Cloudiness near the Date Line has been below average since mid-July. Typically this signal is indicative of La Niña, however, the overall pattern of cloudiness is consistent with a neutral state.

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 five days ending 12 August are weaker than average in the central to western tropical Pacific. These significantly weakened trade winds are likely a result of tropical cyclones on the north side of the equator and may prompt further warming in the tropical Pacific 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.

Most of the eight surveyed international climate models predict warming of central equatorial Pacific sea surface temperatures (SSTs) is likely to resume over the coming months. Most models suggest El Niño thresholds are likely to be reached by the end of the year, with the majority suggesting these thresholds could be met by mid to late spring.

Sea surface temperature (SST) anomalies for July are slightly warmer than average in the Pacific Ocean close to the equator, but within neutral ENSO thresholds. The South Pacific, parts of the Maritime Continent, and large parts of the North Pacific were warmer than average in July.

The July values for NINO3 was 0.4 °C, NINO3.4 0.3 °C, and NINO4 +0.4 °C.

The 30-day Southern Oscillation Index (SOI) to 12 August was −2.9, and the 90-day SOI was −1.9. These values are both well within the neutral ENSO range.

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 weekly index value to 12 August was +0.16 °C.

Three of the six international climate models surveyed by the Bureau suggest that a short-lived positive IOD may develop.

The four-month sequence of sub-surface temperature anomalies (to July) shows the evolution of a pool of warmer than average water, which has tracked eastward over recent months. July has seen this pool of warmer than average water decrease in strength, but weak warm anomalies were still evident along the equatorial Pacific sub-surface.

Sub-surface temperatures for the five days ending 12 August show a pool of weakly warmer than average water beneath the surface of the western equatorial Pacific between 100 m to 200 m depth. In the eastern equatorial Pacific, a small pool of weakly cooler than average water is surfacing.

The overall state of the sub-surface is consistent with neutral ENSO, but if the warmer than average water in the western Pacific moves eastwards, this could be a precursor to an El Niño event.

Product code: IDCKGEWW00