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

SSTs for January 2022 show weak cool SST anomalies across most of the eastern half of the equatorial Pacific, and weak warm SST anomalies were over parts of the Maritime Continent and the Coral Sea and parts of Queensland's east coast.

Values of the three key NINO indices for January 2022 were: NINO3 −1.0 °C, NINO3.4 −0.7 °C, and NINO4 −0.2 °C.

Sea surface temperatures (SST) in the tropical Pacific Ocean for the week ending 27 February 2022 were cooler than average along the equator in most of the central and eastern Pacific Ocean. Weak warm SST anomalies continued over parts of the Maritime Continent and have strengthted to the north-east and north-west of Australia. Compared to two weeks ago, cool anomalies have strengthened slightly in the central equatorial Pacific, and weakened at the eastern edge of the basin. Overall, sea surface temperatures continue to show a well-developed La Niña pattern.

The latest values of the three NINO indices for the week ending 27 February 2022 were: NINO3 −0.8 °C, NINO3.4 −0.7 °C, and NINO4 −0.3 °C.

Persistent NINO3 or NINO3.4 values cooler than −0.8 °C are typical of La Niña, while persistent values warmer than +0.8 °C typically indicate El Niño.

Trade winds for the 5 days ending 27 February 2022 were close to average in the east and stronger than average in the central to western tropical Pacific. Trade winds have generally been stronger than average in recent weeks and months.

During La Niña there is a sustained strengthening of the trade winds across much of the tropical Pacific, while during El Niño there is a sustained weakening, or even reversal, of the trade winds.

The Madden–Julian Oscillation (MJO) recently weakened while in the Australian region and is now indiscernible. Most climate models suggest the MJO is likely to remain weak for the coming fortnight, meaning it is unlikely to influence tropical climate during this time.

The Indian Ocean Dipole (IOD) is currently neutral. The latest weekly value of the IOD index to 27 February 2022 was −0.46 °C.

While the monsoon trough is over the tropical Indian Ocean, it changes wind patterns and IOD events are unable to form. This typically lasts from December to April. A neutral IOD has little influence on Australian climate.

All five international climate models surveyed by the Bureau indicate the IOD will remain neutral for the coming autumn months. Model outlooks issued at the present time of year have low accuracy (skill) beyond autumn. The Bureau will continue to monitor model outlooks as winter approaches.

Cloudiness near the Date Line has been consistently below average (positive OLR anomalies) since June 2021. Across parts of the Maritime Continent cloudiness has been slightly above average during February, while around the Gulf of Carpentaria and far northern Australia cloudiness has been below average. Cloudiness anomalies across northern Australia have become closer to average over the last week or so.

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

The four-month sequence of equatorial Pacific sub-surface temperature anomalies (to 28 February 2022) shows cool anomalies persist across the sub-surface of the eastern half of the equatorial Pacific, although anomalies were much weaker during February than during January. For February, waters were one-and-a-half to three degrees cooler than average across the top 100 m of the equatorial Pacific east of 110°W.

Warm anomalies continue across parts of the central to western equatorial Pacific. These warm anomalies reached more than three degrees above average between 140°E and the Date Line (180°E) between 100 m and 175 m depth. Compared to January, warm anomalies have also weakened during February.

For the five days ending 27 February 2022, sub-surface temperatures were slightly warmer than average across the western half of the equatorial Pacific, reaching more than 2 degrees warmer than average between 100 m and 200 m depth from around 150°W to the western edge of the basin. Weak warm anomalies have also emerged in part of the shallow sub-surface of the eastern edge of the equator, reaching 2 degrees warmer than average at around 110°W and 50 m depth. These warm anomalies in the eastern equatorial Pacific have drifted eastward over recent weeks. The emergence and strengthening of warm anomalies in the sub-surface of the eastern equatorial Pacific typically foreshadow a breakdown of a La Niña event.

The 2021–22 La Niña is past its peak, with outlooks indicating a return to neutral El Niño–Southern Oscillation (ENSO) levels—neither La Niña nor El Niño—during the southern hemisphere autumn. As La Niña weakens, it will continue to influence global weather and climate.

Atmospheric and oceanic indicators over the Pacific remain at La Niña levels. Eastern tropical Pacific sea surface temperatures remain cooler than average despite a slow warming of deeper waters. Warming below the surface of the Pacific Ocean typically foreshadows a breakdown in La Niña, and typically occurs in the southern autumn. In the atmosphere, several indicators remain at La Niña levels, including decreased cloudiness along the Date Line, strengthened trade winds in the western Pacific, and a positive Southern Oscillation Index (SOI).

La Niña increases the likelihood of tropical cyclones within the Australian region, as well as increasing the chances of above average rainfall across large parts of eastern Australia during autumn.

The Madden–Julian Oscillation (MJO) recently weakened while in the Australian region and is now indiscernible. Most climate models suggest the MJO is likely to remain weak for the coming fortnight, meaning it is unlikely to influence tropical climate during this time.

The Southern Annular Mode (SAM) is neutral and is forecast to remain neutral over the coming three weeks. A neutral SAM has little influence on Australian climate.

The Indian Ocean Dipole (IOD) is neutral. It typically has little influence on global climate from December to April due to the influence of the monsoon.

Climate change continues to influence Australian and global climate. Australia's climate has warmed by around 1.47 °C for the 1910–2020 period. Rainfall across northern Australia during its wet season (October–April) has increased since the late 1990s. In recent decades there has been a trend towards a greater proportion of rainfall from high intensity short duration rainfall events, especially across northern Australia.

The Southern Annular Mode (SAM) index is neutral. It is forecast to generally remain neutral over the next three weeks. A neutral SAM has little influence on Australian climate.

La Niña is active in the tropical Pacific Ocean, but is past its peak. Autumn is the usual time of the year in which ENSO events decay and return to neutral.

Most of the seven international climate models surveyed by the Bureau anticipate the strength of the La Niña will ease over the next three months, with a return to neutral ENSO conditions (neither El Niño nor La Niña) in mid-autumn.

Four models indicate sea surface temperatures in the central equatorial Pacific will meet or exceed La Niña thresholds during April. By May only two models continue to exceed the threshold, with the other five firmly neutral.

La Niña increases the chance of above average rainfall across much of northern and eastern Australia during summer, with a weaker influence during autumn. It is important to note that significant weather can still occur as La Niña comes to an end, especially as we approach the peak of the tropical cyclone season.