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

SSTs for June 2022 were generally close to average close to the equator across the Pacific, but SSTs were slightly cooler than average over much of the tropical central and eastern Pacific south of the equator, and in some scattered areas north of the equator. Cool anomalies were strongest close to South America. Warm SST anomalies were present over much of the Maritime Continent.

Compared to May, cool anomalies have weakened, while warm anomalies around northern Australia and to Australia's north-east have strengthened.

Values of the three key NINO indices for June 2022 were: NINO3 −0.3 °C, NINO3.4 −0.4 °C, and NINO4 −0.3 °C.

For the week ending 17 July 2022, sea surface temperatures (SST) in the tropical Pacific Ocean were generally near average close to the equator, except for slightly cooler than normal temperatures on and to the west of the Dateline along the equator and small pockets of weak warm anomalies in parts of the eastern equatorial Pacific east of 150°W. Cool SST anomalies are persisting over much of the tropical central and eastern Pacific south of the equator.

Warm SST anomalies continue over the southern Maritime Continent and around much of Australia.

The latest values of the three NINO indices for the week ending 17 July 2022 were: NINO3 0.0 °C, NINO3.4 −0.3 °C, and NINO4 −0.6 °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.

The 30-day Southern Oscillation Index (SOI) for the 30 days ending 17 July 2022 was +12.5. The 90-day SOI value was +16.6.

The 30-day SOI has fallen over the past fortnight to more moderate positive values. Much of the persistent positive SOI signal is due to high pressures over Tahiti.

Sustained positive values of the SOI above +7 typically indicate La Niña while sustained negative values below −7 typically indicate El Niño. Values between +7 and −7 generally indicate neutral conditions.

Trade winds for the 5 days ending 17 July 2022 were stronger than average over most of the tropical Pacific with the largest anomalies occurring in the western half of the tropical Pacific. This recent strengthening is likely due to recent Madden-Julian Oscillation activity over the Maritime Continent. Anomalies were close to average over the far eastern tropical Pacific.

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) has recently weakened over the Maritime Continent. Some models anticipate it may strengthen over the African region in coming days. 

A strengthening of the MJO over the African region and Indian Ocean is often associated with reduced cloudiness over northern parts of the Maritime Continent, and enhanced rainfall over parts of north-east Australia.

The latest Indian Ocean Dipole (IOD) index value for the week ending 17 July 2022 was −1.0 °C. Increasingly negative values of the IOD index over recent weeks are consistent with an emerging negative IOD event. For the week ending 10 July 2022, the value of -1.1 °C was the lowest IOD index value since spring 2016, and the sixth strongest weekly value since at least late 2001.

The IOD index has been below zero for ten consecutive weeks, with the IOD index value continuously at or below the threshold (−0.4 °C) for the most recent six weeks.

Cool anomalies are present close to the Horn of Africa in the north-west of the Indian Ocean basin, while weak warm SSTs anomalies continue across the east of the Indian Ocean between Indonesia and Australia. The establishment of a clear gradient in the temperature anomalies across the Indian Ocean is consistent with a developing negative Indian Ocean Dipole pattern.

All five international climate models surveyed by the Bureau indicate a negative IOD is likely to persist through to November.

A negative IOD increases the chances of above average winter–spring rainfall for much of Australia. It also increases the chances of warmer days and nights for northern Australia.

Cloudiness near the Date Line had been consistently below average (i.e. positive outgoing longwave radiation, or OLR, anomalies) since June 2021. It continued to be below average through June 2022, although with some periods of close to average anomalies since late May, most recently during late June and currently in the middle of July.

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 June 2022) shows a small area of weak cool anomalies persist in the far eastern equatorial Pacific for June, but warm anomalies dominate across the majority of the tropical subsurface.

Warm anomalies have increased their eastward extent month-on-month across autumn and the first month of winter. For June, warm anomalies spanned nearly the full column depth west of 140°E, rising to 50 to 150 m depth around 120°W.

For the five days ending 17 July 2022, sub-surface temperatures along the equator were mostly close to average, with an area of warm anomalies in the east. In the eastern equatorial Pacific, temperatures were more than 3 degrees warmer than average between 50 m and 100 m depth in a region extending east of 130°W, and more than 2 degrees warmer than average at 100m in depth in the far western Pacific. Compared to two weeks ago, these regions of warm anomalies have decreased in strength. An area of weak cool anomalies has expanded in size in the central tropical Pacific between 100 and 150 m depth when compared to two weeks ago.

The Indian Ocean Dipole (IOD) index has been very close to or exceeded negative IOD thresholds (i.e. at or below −0.4 °C) over the past six weeks. If, as forecast, negative IOD thresholds are exceeded for the next fortnight, 2022 will be considered a negative IOD year. All climate model outlooks surveyed indicate negative IOD conditions are likely for the remainder of winter and spring. A negative phase of the IOD is associated with above average winter–spring rainfall for much of Australia.

The Bureau's ENSO Outlook is at La Niña WATCH, meaning there is about a 50% chance (double the normal likelihood) of La Niña forming later in 2022. La Niña events increase the chance of above average winter–spring rainfall across much of northern and eastern Australia.  

El Niño–Southern Oscillation (ENSO) ocean indicators are at neutral levels. However, some atmospheric indicators, such as the Southern Oscillation Index, show a residual La Niña-like signal. Trade winds have recently re-strengthened in the central to western Pacific, partially in response to Madden–Julian Oscillation activity. 

Most climate models surveyed by the Bureau indicate ENSO is likely to remain neutral through the southern hemisphere winter. But four of the seven models surveyed by the Bureau suggest La Niña could return in spring, with three models persisting at neutral ENSO levels.  

The Madden–Julian Oscillation (MJO) is currently weak. Some models suggest the MJO may strengthen in the African region in the coming days, which can bring above average rainfall to northeast Queensland.   
 
The Southern Annular Mode (SAM) index is currently positive, with neutral to positive values forecast for the following three weeks. Positive SAM has a drying influence for parts of south-west and south-east Australia, while neutral SAM has little influence on Australian rainfall. 

Climate change continues to influence Australian and global climate. Australia's climate has warmed by around 1.47 °C for the 1910–2020 period. Southern Australia has seen a reduction of 10–20% in cool season (April–October) rainfall 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.

The Southern Annular Mode (SAM) index is currently positive, with positive values generally persisting since late June. Values in late June were strongly positive.

Over the next few days SAM values are expected to return to near neutral, with neutral to positive values generally anticipated over the coming weeks.

Neutral SAM has little influence on Australian rainfall, while positive SAM has a drying influence for parts of south-west and south-east Australia at this time of year.

The El Niño–Southern Oscillation is currently neutral. However, some models suggest that La Niña may re-form during the southern hemisphere spring later in 2022.

Five of seven surveyed international climate models predict neutral but cooler than average temperatures in the central tropical Pacific to persist throughout the southern winter, while two show stronger cooling, reaching La Niña thresholds (−0.8 °C) by late winter. In October, four of the seven models indicate SSTs in the central equatorial Pacific Ocean will reach or exceed La Niña threshold values. Three of the seven models anticipate that the current ENSO-neutral state will continue through to at least November.

While back-to-back La Niña events are not uncommon, and have occurred in approximately half of all past events since 1900, three in a row is less common and has only occurred three times since 1900: 1954–57, 1973–76, and 1998–2001.

Despite the end of the 2021–22 La Niña, the Bureau's long-range climate outlook remains wetter than average for most of Australia, reflecting a range of climate drivers including a developing negative Indian Ocean Dipole, and warmer than average waters around Australia.