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 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 temperature (SST) anomalies in the tropical Pacific Ocean have eased back from their December highs over the past three weeks. SSTs remain warmer than average across the central and eastern tropical Pacific, and are close to average across most of the Maritime Continent.

SSTs are also warmer than average in a broad band across the southern Pacific extending from the tropics in the west to around 30°S in the east; the opposite of what is expected in a typical El Niño.

SSTs for all three NINO regions have cooled slightly compared to three weeks ago, and are now within the ENSO neutral range. The latest values of the key NINO indices in the tropical Pacific for the week ending 6 January are: NINO3 +0.6 °C, NINO3.4 +0.6 °C and NINO4 +0.7 °C. The NINO3.4 region has cooled by 0.4 of a degree since early December.

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 warmer than average across the Great Australian Bight, up the New South Wales coast, and across Bass Strait and the Tasman Sea. SSTs are more than two degrees warmer than average in much of the area between Australia and New Zealand.

Elsewhere around Australia SSTs are generally close to average temperatures.

Tropical Pacific Ocean surface waters have returned to ENSO-neutral temperatures after exceeding El Niño levels in November and early December. The Bureau's ENSO Outlook remains at El Niño ALERT.

While waters at and beneath the surface of the tropical Pacific have been warmer than average since mid-2018, atmospheric indicators of ENSO such as cloudiness, trade winds and the Southern Oscillation Index (SOI) have not responded and have mostly remained neutral. For an El Niño to become established, the atmosphere needs to reinforce and respond to the warmer waters at the ocean's surface. This reinforcement is what allows the widespread global effects on weather and climate to occur.

The recent cooling of tropical Pacific waters may partly reflect the movement of the Madden–Julian Oscillation (MJO), which has recently encouraged stronger trade winds over the tropical Pacific. However, the MJO is moving east, weakening the trade winds once again, which may allow the ocean surface to warm again.

Most models indicate sea surface temperatures in the tropical Pacific are likely to remain near El Niño levels at least until early autumn 2019. Models typically have less skill when forecasting through autumn compared with other seasons. If sea surface temperatures do maintain their anomalous warmth through summer, it increases the chance of El Niño emerging in 2019.

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

Please note: due to the US Government shutdown, some of our usual maps are currently unavailable.

Cloudiness near the Date Line has fluctuated around average for the past two months. However, cloudiness near the Date Line has generally been above average more recently. It would typically be well above average during El Niño.

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

Trade winds were stronger than average across the western to central equatorial Pacific during December (green shades), but have trade winds across the western Pacific have been weakened during the first week of January (pink shades).

Due to the US Government shutdown a different trade winds map is displayed this week. The map shows trade winds across the equator varying with time.

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.

The lack of an El Niño-like wind pattern is one of the indicators that the atmosphere and ocean have not coupled, which would be required for an event to become established.

Five of the eight surveyed climate models predict sea surface temperatures (SSTs) will remain above El Niño thresholds through the southern hemisphere summer of 2018–19.

Most models indicate SSTs will drop as autumn progresses, although three models see SSTs increase over the season. By May three models predict El Niño thresholds will be exceeded, while another two are below but close to threshold values.

While the models indicate elevated sea surface temperatures in the tropical Pacific will persist, El Niño onset during summer would be unusual. This is because the seasonal cycle typically favours a decay of the east to west difference in SSTs across the tropical Pacific during summer to autumn.

Sea surface temperatures (SSTs) for December were warmer than average for much of the tropical Pacific Ocean, and much of the southern Pacific.

The December values for NINO3 were +0.8 °C, NINO3.4 +0.8 °C, and NINO4 +0.9 °C.

The 30-day Southern Oscillation Index (SOI) to 6 January was +6.2, and the 90-day SOI was +4.0. The SOI has remained within the neutral ENSO range since early September. There have been fluctuations over recent recent weeks, however during the southern hemisphere summer the SOI is more volatile due to the passage of tropical storms and should therefore be viewed with caution.

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 lack of a clear, sustained El Niño signal in the SOI is one indicator (also see Trade Winds and Cloudiness sections) that the atmospheric circulation required to signal the start of El Niño has not established. This atmospheric coupling is the mechanism which reinforces and sustains El Niño, and facilitates widespread shifts in Australian and global weather and climate.

The Indian Ocean Dipole (IOD) is currently neutral. The latest weekly index value to 6 January was +0.13 °C.

Due to the movement of the monsoon trough in the Indian Ocean, 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.

All of the six international climate models surveyed by the Bureau indicate that the IOD will remain neutral into autumn 2019.

The four-month sequence of sub-surface temperature anomalies (to December) shows warm anomalies across most of the top 150 m of the equatorial Pacific sub-surface, and small areas of cool anomalies just below this level. Compared to previous months, warm anomalies in the sub-surface have weakened, although small parts of the sub-surface to the west of the Date Line remain more than two and a half degrees warmer than average.

Temperatures for the seven days ending 31 December show warmer than average waters in the top 150 m of the sub-surface of the equatorial Pacific. Warm anomalies in the sub-surface of the eastern equatorial Pacific reach more than three degrees above average. Weak cool anomalies are present in the central equatorial Pacific sub-surface below 150 m.

Waters across the top 150 m of the sub-surface have cooled a little (a shift towards average temperatures) since mid-December. However, warm anomalies have continued to progress towards the eastern equatorial Pacific sub-surface. This eastward shift of anomalously warm water is a typical precursor of El Niño.

Due to the US Government shutdown, Pacific Ocean subsurface maps are currently unavailable. The map shown here is from an experimental (POAMA) model analysis and hence caution should be taken when directly comparing to other analysis systems.

Product code: IDCKGEWW00