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 3 July 2022, sea surface temperatures (SST) in the tropical Pacific Ocean were generally near average close to the equator, however small pockets of weak warm anomalies were present along the equator in parts of the eastern equatorial Pacific east of 150°W. SSTs were slightly cooler than average over much of the tropical central and eastern Pacific south of the equator.

Cool anomalies continue along the coastline of South America, with the strength of cool SST anomalies greatest here compared to the rest of the Pacific.

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 3 July 2022 were: NINO3 −0.1 °C, NINO3.4 −0.3 °C, and NINO4 −0.5 °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 3 July 2022 was +20.2. The 90-day SOI value was also 19.5.

The 30-day SOI remains firmly elevated despite the return to a neutral ENSO phase. Much of the 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 3 July 2022 were close to average over the eastern half of the tropical Pacific, and stronger than average in the western 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) is currently in the western Maritime Continent, but models anticipate the MJO signal is likely to weaken in the coming days.

While over the Maritime Continent, the MJO typically enhances rainfall over parts of north-east Australia and the northern Maritime Continent, and can also strengthen trade winds over the tropical Pacific. If the MJO pulse weakens as forecast, its influence on rainfall and wind patterns is expected to diminish.

The latest Indian Ocean Dipole (IOD) index value for the week ending 3 July 2022 was −0.69 °C. Increasingly negative values of the IOD index over recent weeks are consistent with development of an emerging negative IOD event.

The IOD index has been below zero for eight consecutive weeks, with the IOD index value continuously below threshold (−0.4 °C) for the most recent three weeks, with a fourth week close to the threshold.

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 IOD index values will meet the negative threshold during July, with all five anticipating a negative IOD is likely to persist through August 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 during late May to early June, and again in late June and early 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 3 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. Compared to two weeks ago, warm anomalies have increased in strength in the eastern equatorial Pacific. An area of weak warm anomalies also continues in the western end of the equatorial sub-surface, but the strength of anomalies there has decreased slightly 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 four weeks, meaning a negative IOD event is increasingly likely in 2022. All climate model outlooks surveyed indicate a negative IOD event is likely for the coming months. 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.

Sea surface temperatures are currently warmer than average around much of the Australian coastline, particularly to the north and west. This pattern is likely to increase the chance of above average winter–spring rainfall for Australia.

The 2021–22 La Niña event has ended. However, observations and climate model outlooks suggest La Niña may re-form later in 2022. As a result, the Bureau's ENSO Outlook status is at La Niña WATCH. La Niña WATCH means there is around a 50% chance of La Niña forming later in 2022. This is approximately double the normal likelihood. La Niña events increase the chance of above average winter–spring rainfall across much of northern and eastern Australia.

El Niño–Southern Oscillation (ENSO) indicators are mostly at neutral levels. Tropical Pacific sea surface temperatures have continued to warm and are now mostly close to average levels. Similarly, beneath the surface, water temperatures are close to average, or slightly warmer than average in the east. Trade winds are also generally close to average strength. However, some atmospheric indicators continue to show a La Niña-like signal, including cloudiness near the Date Line and the Southern Oscillation Index (SOI).

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

The Madden–Julian Oscillation (MJO) is currently in the western Maritime Continent region. Models suggest this MJO signal is likely to weaken in the coming days. The MJO in this region typically enhances rainfall over parts of north-east Australia and the northern Maritime Continent, and can also strengthen trade winds over the tropical Pacific. If the MJO pulse weakens as forecast, its influence on rainfall and wind patterns is expected to diminish.

The Southern Annular Mode (SAM) index is currently positive, and while SAM values are expected to briefly return to neutral within the next week, neutral to positive values are generally anticipated for the remainder of July. 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 persisting since late June. Values in late June were strongly positive.

Over the next few days SAM values are expected to briefly return to 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.

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.