The Bureau of Meteorology (BOM) has officially declared the end of La Niña, in the same breath as an El Niño warning.
The 2022–2023 La Niña has ended after more than 6 soggy months of summer bringing devastating floods and dampness.
However, celebrations have been put on hold as the BOM quickly shifted from “in La Niña” straight up to “El Niño Watch”.
Eastern Pacific temperatures are warming rapidly, and at the current rate, the western part of the ocean will be pushing El Niño within months.
A significant amount of warmer-than-average water exists in the western and central tropical Pacific sub-surface, and warmer-than-average sea surface temperatures (SST) have emerged in parts of the eastern tropical Pacific in recent weeks. So while most models suggest the El Niño-Southern Oscillation (ENSO) forecast will remain neutral over autumn, there’s twice the normal likelihood that El Niño will occur.*
What is El Niño?
El Niño is a climate phenomenon that occurs in the Pacific Ocean. In El Niño the sea surface temperatures in the central and eastern tropical Pacific warm up. This warming can have significant impacts on our weather patterns.
El Niño occurs when the trade winds that blow from east to west across the Pacific Ocean weaken or even reverse. As a result, warm water that has piled up in the western Pacific moves eastward, warming the sea surfaces in the eastern Pacific. This warming can disrupt the normal patterns of atmospheric circulation, affecting weather patterns in many regions.
The impacts of El Niño n Australia are generally felt as drought and wildfires. It can also affect ocean currents and marine ecosystems, leading to changes in fish populations and coral bleaching.
When was the last El Niño?
The last time El Niño came to town was in 2015, bringing severe drought to Tasmania, Victoria, tropical Queensland and southern South Australia.
*About 50% of the time a WATCH was reached, an ENSO event subsequently occurred