Climate Driver Update history
Climate drivers in the Pacific, Indian and Southern oceans and the Tropics

In the Bureau analysis dataset, sea surface temperatures (SSTs) for February 2024 were warmer than average across the tropical Pacific Ocean. Between 10°S and 10°N, SST anomalies were more than 1.2 °C warmer than the long-term (1961–1990) average in the central and eastern Pacific Ocean. The extent and magnitude of warm anomalies across the equatorial Pacific has decreased compared to January 2024.

Warm SST anomalies up to 2 °C above average also continued off most of the eastern Australian coast from central Queensland southwards, south of Australia, and in the Tasman Sea, increasing to up to 3 °C above average east of Tasmania. When compared to January 2024, SST anomalies have generally decreased, especially in the eastern Tasman Sea and the northern Coral Sea. Small regions of cool normal anomalies, up to 1.2 °C below the 1961–1990 average, were present in the Great Australian Bight.

Cool anomalies off the Pilbara coast in Western Australia present in January 2024, have mostly dissipated. Warm anomalies persist in the Maritime Continent, particularly in its northern region.

The Bureau's long-range forecasts indicate warmer than average SSTs (reaching 1.2 °C warmer than average) will likely continue off the coast of northern, eastern, and south-west Australia through till at least June.

For the week ending 3 March 2024, sea surface temperatures (SSTs) in the Bureau dataset were warmer than average across the equatorial region of the tropical Pacific Ocean, with anomalies between 0.8 °C and 2 °C warmer than average across the equatorial Pacific. Large regions of warm anomalies between 0.8 °C and 2 °C were also present in areas of the South Pacific.

Closer to Australia, warm SST anomalies of 1.2 °C to 2 °C extend across much of the western Pacific Ocean, around Australia's eastern, western, and southern coastlines, and around the Maritime Continent. SST anomalies more than 2 °C above average were also present off the north coast of New South Wales and the east coast of Tasmania.

Compared to last fortnight, cool SSTs anomalies off the coast of the Great Australian Bight have warmed and largely dissipated.

The latest values of the three NINO indices in the Bureau dataset for the week ending 3 March 2024 were: NINO3, +1.28 °C; NINO3.4, +1.23 °C; and NINO4, +1.11 °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 30–, 60– and 90-day Southern Oscillation Index (SOI) values for the period ending 3 March 2024 were −11.0, −4.1 and −3.8, respectively. Compared to last fortnight, the 30-day SOI has become more positive while the 60-day and 90-day values have remained similar. The 30-day SOI can have increased variability in the southern hemisphere summer due to local weather systems over northern Australia or Tahiti.

Trade winds for the 5 days ending 3 March 2024 were generally close to average over most of the Pacific. There was a small area of stronger than average trade winds west of the Date Line.

During an El Niño event, there is typically a sustained weakening, or even reversal, of trade winds across much of the tropical Pacific.

The Madden–Julian Oscillation (MJO) is currently in the eastern Indian Ocean. The MJO is forecast to move into the Maritime Continent in the coming days and progress eastwards towards the Western Pacific over the coming fortnight. When the MJO is in the eastern Indian Ocean, increased cloudiness tends to occur over the eastern Indian Ocean and western parts of south-east Asia. As the MJO shifts into the Maritime Continent, increased cloudiness tends to occur over parts of the far north of Australia and the islands of south-east Asia, Indonesia and Papua New Guinea.

The Indian Ocean Dipole (IOD) is currently neutral, with the IOD index being −0.42 °C for the week ending 3 March 2024. IOD events are typically unable to form between December and April. This is because the monsoon trough shifts south over the tropical Indian Ocean changing wind patterns and preventing the IOD pattern from forming. 

International climate models surveyed by the Bureau suggest IOD values will remain neutral until at least April.

Sea surface temperatures (SSTs) for the week ending 3 March 2024 were up to 2 °C warmer than the 1961–1990 average across much of the tropical Indian Ocean, with warm anomalies also extending south-eastwards to waters south of Australia. Compared to last fortnight, waters in the eastern Indian Ocean have continued to warm in the central and eastern tropical Indian Ocean while cooling slightly south of 20°S.

Outgoing Longwave Radiation (OLR) around the equatorial Date Line is currently close to the climatological average, indicating a decrease in cloudiness compared to recent weeks. OLR was mostly below average since mid-September 2023, tending positive for most of January 2024, returning to below average for most of February.

The 4-month sequence of equatorial Pacific sub-surface temperature anomalies (to 29 February 2024) shows weak warm anomalies across the top 25 m of the equatorial Pacific during February. Cool anomalies are present below this shallow layer of warm anomalies exceeding more than 3 °C cooler than average westwards of 170 °W.

The depth and magnitude of warm anomalies has significantly decreased over the November to February period, with weak warm anomalies less than 2 °C warmer than average, persisting only close to the surface in February. The magnitude and extent of cool anomalies has also increased across the past few months, and has spread eastwards. This sub-surface pattern of a layer of warmer than average waters above a layer of cooler than average waters is typical of the declining phase of El Niño.

For the 5 days ending 3 March 2024, sub-surface temperatures were more than 2 °C warmer than average across the top 50 m of the equatorial Pacific east of 125°W. Elsewhere, anomalies in the western and central Pacific were generally within 1 °C of average. An area of cool anomalies, reaching more than 3 °C cooler than average, was present between 50 and 100 m depth in the eastern equatorial Pacific between 110°W and 140°W.

Compared to last fortnight, the magnitude of warm anomalies in the central and eastern Pacific has decreased, while the area of cool anomalies below 50 m has continued to move eastwards.

El Niño persists, although a steady weakening trend is evident in its oceanic indicators. Climate models indicate sea surface temperatures in the central tropical Pacific are expected to continue declining and are forecast to return to ENSO-neutral in the southern hemisphere autumn 2024.

Atmospheric indicators are mixed but are consistent with a steadily weakening El Niño. Cloudiness near the equatorial Date Line has decreased over the last fortnight, returning to the climatological average.  The 30-day Southern Oscillation Index (SOI) is currently less than -7.0, characteristic of an El Niño state, but indicative of ENSO-neutral conditions over the 60- and 90-day periods. Temporary fluctuations of ENSO atmospheric indicators are common during summer and are not an indication of El Niño strength.

International climate models suggest the central tropical Pacific Ocean will continue to cool in the coming months, with four out of seven climate models indicating the central Pacific is likely to return to neutral El Niño–Southern Oscillation (ENSO) levels by the end of April (i.e., neither El Niño nor La Niña), and all models indicating neutral in May. ENSO predictions made in autumn tend to have lower accuracy than predictions made at other times of the year. This means that current forecasts of the ENSO state beyond May should be used with caution.

Based on the historical record from 1900, around 50% of El Niño events have been followed by an ENSO-neutral year, and 40 to 50% have been followed by La Niña. However, global oceans have warmed significantly over the past 50 years. The oceans have been the warmest on record globally between April 2023 and January 2024. These changes may impact future predictions of ENSO events, if based solely on historical climate variability.

The Indian Ocean Dipole (IOD) is neutral. IOD events are typically unable to form between December and April. This is because the monsoon trough shifts south over the tropical Indian Ocean changing wind patterns and preventing the IOD pattern from forming.

The Southern Annular Mode (SAM) is currently neutral, as of 3 March. Forecasts indicate SAM will remain neutral over the coming fortnight.

The Madden–Julian Oscillation (MJO) is currently in the eastern Indian Ocean. The MJO is forecast to move into the Maritime Continent in the coming days and progress eastwards towards the Western Pacific over the coming fortnight. When the MJO is in the eastern Indian Ocean, increased cloudiness tends to occur over the eastern Indian Ocean and western parts of South East Asia. As the MJO shifts into the Maritime Continent, increased cloudiness tends to occur over parts of the far north of Australia and the islands of South East Asia, Indonesia and Papua New Guinea.

The annual global mean temperature for the 12 months from February 2023 to January 2024 was the highest on record, with Copernicus reporting that it was 1.52 °C above the 1850–1900 pre-industrial average. However, this does not mean that the 1.5 °C target referred to in the Paris Agreement has been exceeded as the magnitude of global warming is assessed using multi-year averages, and this is only one 12-month period.

Australia's climate has warmed by 1.50 ± 0.23 °C between 1910 and 2023, leading to an increase in the frequency of extreme heat events. In recent decades, there has also been a trend towards a greater proportion of rainfall from high intensity, short duration rainfall events, especially across northern Australia during the wet season. April to October rainfall has declined across southern Australia in recent decades, due to a combination of long-term natural variability and changes in atmospheric circulation caused by an increase in greenhouse gas concentrations.

The Southern Annular Mode (SAM) index is currently neutral as at 3 March 2024. Forecasts indicate the SAM will remain neutral over the coming fortnight.  A neutral SAM has little influence on Australian rainfall patterns.

International model forecasts indicate cooling of the central and eastern equatorial Pacific is expected to continue over the coming months. Sea surface temperatures in the tropical Pacific are expected to return to neutral levels (neither El Niño nor La Niña) by the end of April 2024. Four out of seven climate models indicate the central Pacific is likely to return to ENSO-neutral levels in April, with all models indicating neutral in May.

In July, five out of seven climate models suggest ENSO will remain neutral, with two models suggesting sea surface temperatures cooling to La Niña levels. However, ENSO predictions made in late summer and early autumn tend to have lower accuracy than predictions made at other times of the year. This means that current forecasts of the ENSO state beyond June should be used with caution.