MELBOURNE, Australia – The El Niño–Southern Oscillation (ENSO) is currently neutral, reports the Bureau of Meteorology of the Australian Government in its latest update. Sea surface temperatures (SSTs) in the central Pacific have been cooling since December 2023. This surface cooling is supported by a cooler than average sub-surface in the central and eastern Pacific.
During June, the rate and extent of cooling both at the surface and at depth has slowed. Cloud and surface pressure patterns are currently ENSO-neutral.
Climate models suggest that SSTs in the central tropical Pacific are likely to continue to cool for at least the next 2 months. From September, 4 of 7 climate models suggest SSTs are likely to remain at neutral ENSO levels, and the remaining 3 suggest the possibility of SSTs reaching La Niña levels (below −0.8 °C).
The Bureau’s ENSO Outlook is at La Niña Watch due to early signs that an event may form in the Pacific Ocean later in the year. A La Niña Watch does not guarantee La Niña development, only that there is about an equal chance of either ENSO remaining neutral or a La Niña developing. Early signs of La Niña have limited relevance to mainland Australia and are better reflections of conditions in the tropical Pacific.
The Indian Ocean Dipole (IOD) is currently neutral. The latest model outlooks indicate that the IOD will remain neutral until at least early spring, beyond which IOD predictability is low.
Global sea surface temperatures (SSTs) have been the warmest on record for each month between April 2023 and June 2024. These global patterns of warmth differ to historical global patterns of sea surface temperatures associated with ENSO and IOD; therefore, future predictions based on historical SSTs during past ENSO or IOD 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 neutral (as at 6 July). Forecasts indicate the index is expected to briefly reach negative values this week, then move towards positive values by mid-July. In winter, a positive SAM typically decreases rainfall for some parts of far southern Australia and increases rainfall in parts of the east. Predictability of the SAM beyond two weeks is typically low.
The Madden–Julian Oscillation (MJO) is weak to moderate in strength in the eastern Indian Ocean (as at 7 July). Model forecasts suggest it is expected to remain weak for the coming fortnight. A weak MJO has little impact on Australian rainfall.
