MELBOURNE, Australia – El Niño continues and is near its end. Climate models indicate sea surface temperatures in the central tropical Pacific are expected to return to ENSO-neutral later in autumn 2024, reports the Bureau of Meteorology of the Australian Government in its latest update.
Oceanic indicators such as tropical Pacific sea surface temperatures have been steadily cooling since December but are still meeting El Niño thresholds. Atmospheric indicators are consistent with a decaying El Niño. Cloudiness near the equatorial Date Line is below average, opposite to that expected during an active El Niño. The 90-day Southern Oscillation Index (SOI) is currently −3.0, indicative of ENSO-neutral conditions.
International climate models suggest the central tropical Pacific Ocean will continue to cool in the coming months, with four out of seven climate models indicating the central Pacific is likely to return to neutral El Niño–Southern Oscillation (ENSO) levels by the end of April (i.e., neither El Niño nor La Niña), and all models indicating neutral in May.
While four out of seven international models are predicting a La Niña by late winter, El Niño and La Niña predictions made in early autumn tend to have lower accuracy than predictions made at other times of the year. This means that current forecasts of the ENSO state beyond May should be used with caution. ENSO forecasts have historically had their lowest skill for forecasts issued in April, with skill increasing from May.
The oceans have been the warmest on record globally since April 2023. Sea surface temperatures continue to increase, with temperatures in February 2024 setting a record for that month, and March 2024 on track to be the warmest March on record (final data for March is not yet available).
The global pattern of warmth is affecting the typical historical global pattern of sea surface temperatures associated with ENSO variability. As the current global ocean conditions have not been observed before, inferences of how ENSO may develop in 2024 that are based on past events may not be reliable.
Although the most recent value of the Indian Ocean Dipole (IOD) index (+0.95 °C) is above the positive IOD threshold, the IOD is neutral. Sustained values of the IOD index above the threshold are required for an IOD event to form. The eastern Indian Ocean has cooled in recent weeks, due to increased monsoonal activity in the area, including tropical low 08U, which developed into Severe Tropical Cyclone Nathan.
The Southern Annular Mode (SAM) is currently positive, as of 2 April. Forecasts indicate SAM will remain positive for almost a week before it returns to neutral.
The Madden–Julian Oscillation (MJO) has moved into the western Indian Ocean and has weakened. Most climate models surveyed indicate that the weak MJO will likely move eastward across the Indian Ocean and the Maritime Continent the coming week and into the Western Pacific by mid-April.
