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

In the tropical Pacific Ocean, July sea surface temperatures (SSTs) were:

• up to 1.2 °C warmer than average across much of the western tropical Pacific Ocean, reaching up to 2 °C warmer than average for the far east
• up to 2 °C cooler than average in patches of the equatorial Pacific, east of 140°W, and parts of the South American coast.

In Australian coastal waters, July sea surface temperatures (SSTs) were:

• up to 2 °C warmer than average in waters surrounding most of Australia, and up to 3 °C warmer than average to the south-west of the mainland and south-east of Tasmania
• up to 2 °C cooler than average, along the South Australian coast extending to the western Tasmania coast, likely due to enhanced upwelling.

Around the Maritime Continent, July sea surface temperatures (SSTs) were:

• up to 1.2 °C warmer than average to the north of the Maritime Continent.

The Bureau's long-range forecast for September to November indicates SSTs are likely to be:

• up to 1.2 °C warmer than average around the Australian coastal waters
• up to 2 °C warmer than average in the Tasman Sea and south of Tasmania
• up to 2 °C cooler than average in the equatorial Pacific, between 180° and 100°W; and up to 1.2 °C warmer than average for most of the remaining areas of the Pacific.

For the week ending 18 August 2024, sea surface temperatures (SSTs) were:

• up to 2 °C warmer than the 1991–2020 average across much of the tropical Pacific Ocean, reaching up to 4 °C warmer than average for the far eastern equatorial Pacific Ocean
• cooler than average, by up to 2 °C, in parts of the eastern equatorial Pacific, between 150°W and 85°W
• 0.8–2 °C warmer than average around much of Australia's coastline, but warmer around south-west WA and eastern Tasmania where temperatures were up to 3 °C above average
• warmer than average across most of the Maritime Continent, by up to 1.2 °C, but for waters around north-east Papua New Guinea, temperatures were up to 2 °C above average.

The Niño indices for the week ending 18 August 2024 are: Niño3, −0.18 °C; Niño3.4, +0.07 °C; and Niño4, +0.62 °C. These values reflect historically neutral ENSO conditions.

The 30–, 60– and 90-day Southern Oscillation Index (SOI) data are currently unavailable due to technical issues.

Trade wind strength for the 5 days ending 18 August was slightly above average across the western tropical Pacific; elsewhere, the trade wind strength was close to average.

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

• A moderate pulse of the Madden–Julian Oscillation (MJO) is currently in the Indian Ocean (as at 18 August).
• Climate models suggest the pulse will become weak as the MJO progresses to the Maritime Continent over the coming week.
• When the MJO is in the Indian Ocean at this time of year, it typically decreases rainfall over southern Australia.

Current state

• The Indian Ocean Dipole (IOD) is neutral. The IOD index for the week ending 18 August was +0.33 °C.
• Sea surface temperatures (SSTs) for the week ending 18 August 2024 were 0.8 to 2 °C warmer than the 1991–2020 average across much of Indian Ocean, but close to average in the far western and eastern equatorial Indian Ocean.
• Closer to Australia, SSTs were up to 3 °C warmer than average off the south-west coast of Australia and up to 2 °C warmer than average to the north-west of Australia.

Forecast

• Most climate models indicate the IOD is likely to remain neutral throughout spring.
• IOD forecast skill has historically been low at this time of year for forecasts beyond two months ahead.

Cloudiness near the equatorial Date Line is currently below average (as at 18 August).

Equatorial cloudiness near the Date Line typically increases during El Niño (below average OLR) and decreases during La Niña (above average OLR).

The 4-month sequence of equatorial Pacific sub-surface temperature anomalies (to 29 July 2024) shows:

• Persistent cool anomalies in the eastern Pacific reduced in magnitude and spatial extent during July.
• Cool anomalies in the central Pacific restrengthened in July, following a weakening in June, with waters cooling to 3.5 °C below average between 160°E and 110°W, the strongest anomalies between 50–200 m depth.
• Warm anomalies in the top 100 m of the central and western equatorial Pacific (between 130°E and 165°W) reaching up to 1.5 °C warmer than average, strengthening slightly during July.

For the 5 days ending 18 August 2024:

• cool anomalies persisted at depths of 100 to 200 m in the central Pacific sub-surface where waters were 1 to 3 °C cooler than average, with the strongest anomalies at around 125 m depth in the central Pacific (around 155°W)
• compared to the last fortnight, central Pacific sub-surface waters have warmed, and the extent of the cool anomalies has expanded in the western Pacific.

The El Niño–Southern Oscillation (ENSO) is currently neutral.

Sea surface temperatures (SSTs) in the central equatorial Pacific Ocean are ENSO-neutral, having gradually cooled from El Niño levels since December 2023. This cooling is being sustained by deep waters surfacing in the central and eastern Pacific. However, the extent and magnitude of cool water has decreased since last fortnight. Atmospheric patterns, including cloud and trade winds, are currently ENSO-neutral.

Three of 7 climate models suggest the possibility of SSTs in the tropical Pacific exceeding the La Niña threshold (below −0.8 °C) from October, with a fourth just briefly reaching the threshold; the remaining 3 models suggest SSTs are likely to remain at ENSO-neutral values (between −0.8 °C to +0.8 °C ) throughout the forecast period. The ENSO Outlook remains at La Niña Watch. La Niña Watch does not guarantee La Niña development, only that there is about an equal chance of ENSO remaining neutral or La Niña developing during the remainder of 2024.

The Indian Ocean Dipole (IOD) is currently neutral. In recent weeks, the east Indian Ocean has cooled, with the latest weekly IOD index value (as of 18 August) of +0.33 °C. However, most models indicate that the IOD is likely to remain neutral until at least the end of spring.

Global SSTs were the warmest on record for each month between April 2023 and June 2024. July 2024 global SSTs were the second warmest on record, not as warm as July 2023 but much warmer than any other year. August 2024 is currently tracking as the second-warmest August on record. The current global pattern of warmth differs to historical patterns of SSTs associated with ENSO and IOD. This means future predictions of ENSO and IOD based on SSTs during past events may not be reliable. Phenomena such as ENSO and the IOD are only broad indicators of the expected climate. The long-range forecast provides better guidance on local rainfall and temperature patterns.

The Southern Annular Mode (SAM) is negative (as at 17 August). The index is forecast to become neutral during the coming week. During winter, a negative SAM typically increases the likelihood of rain-bearing fronts across southern Australia and decreases rainfall influenced by onshore flow in parts of the east.

A moderate pulse of the Madden–Julian Oscillation (MJO) is currently in the Indian Ocean (as at 17 August). Models suggest the pulse will become weak as the MJO progresses to the Maritime Continent over the coming week. When the MJO is in the Indian Ocean at this time of year, it typically decreases rainfall over southern Australia.

• The Southern Annular Mode (SAM) is negative (as at 17 August). The index is forecast to become neutral in the coming week.
• During winter, a negative SAM typically increases the likelihood of rain-bearing fronts across southern Australia and decreases the chance of rainfall influenced by onshore flow in parts of the east.
• Predictability of the SAM beyond two weeks is typically low.

• ENSO is currently neutral.
• Three of 7 climate models suggest the possibility of SSTs in the tropical Pacific exceeding the La Niña threshold (below −0.8 °C) from October, with a fourth just briefly reaching the threshold; the remaining 3 models suggest SSTs are likely to remain at ENSO-neutral values (between below −0.8 °C to +0.8 °C ) throughout the forecast period.
• Historically, the ENSO forecast skill, for up to 4 months ahead, is high at this time of year.