The first El Niño in three years could develop during the coming months, raising the possibility of worsening drought and extreme heat across Australia in 2026.
El Niño refers to a spell lasting about nine to 12 months of abnormally warm water temperatures across the tropical Pacific — a pattern that disrupts weather patterns across the globe.
Australia is particularly vulnerable, with past events responsible for many of our driest years on record, while globally El Niño years and the following year typically bring record-high temperatures and increased extreme weather.
How likely is El Niño in 2026
The Pacific is currently far from El Niño — in fact, it has been in the opposite cool state, La Niña, since November.
While La Niña is often associated with rain and flooding in Australia, the current edition is weak and in decline, paving the way for the transition season from March to June.
This critical period determines if and how sea surface temperatures will swing for the remainder of the year.
Around 50 per cent of years stay neutral, while the remaining years are split between a shift towards El Niño or La Niña, although occasionally the transition does not occur until late winter.
However, according to the latest modelling, the odds in 2026 strongly favour rapid warming of tropical Pacific waters through autumn, including the Bureau of Meteorology (BOM) model, which indicates a 57 per cent chance of El Niño by May, increasing to 99 per cent by mid-winter.
[CORE: ACCESS-S2]A survey of all models from international agencies indicates that the chances of El Niño this year are closer to 60-70 per cent, but an important caveat is that long-range modelling can be unreliable in February, as it immediately precedes the 'predictability barrier' of the transition season.
This uncertainty is reflected in the official commentary, with the National Oceanic and Atmospheric Administration's (NOAA)
"There are growing chances of El Niño, though there remains uncertainty given the lower accuracy of model forecasts through the spring [austral autumn]," the NOAA said.
The BOM's latest commentary is even more cautious:
"It should be noted that this is a very long lead time for such a prediction, and forecasts beyond autumn are highly uncertain," the BOM said.
Essentially, this means that while El Niño is more likely than during an average year, it could be difficult to gauge the true probability for another month or two.
However, there is another clue that may hint El Niño is looming — seasonal forecasts for rain favour a dry autumn and start to winter.
For example, the latest ACCESS-S2 precipitation outlook below displays a greater than 65 per cent probability that rain in the April to June quarter will be below normal for most of Australia.
What an El Niño year would look like
An El Niño in 2026 would extend the run of active Pacific years (either La Niña or El Niño ) to seven in a row, equalling the current record of seven from 1969 to 1975.
If it does emerge, cloud and rain will migrate from Australian longitudes toward the warmer waters of the central Pacific, increasing the probability of below-average precipitation. However, the shift is variable both geographically and by season.
An analysis of 14 past El Niño events reveals the greatest impact on rain (in Australia) is from late autumn through to mid-spring — including a reduction in winter totals by a national average of 32 per cent.
Spring rain falls by an average of around 20 per cent, and autumn drops 14 per cent, while there is little relationship to summer falls.
The chart below shows annual national rainfall this century, noting that La Niña is not the polar opposite of El Niño — bringing above-average rainfall for a longer period and at higher intensity.
[CORE ENSO RAIN]While there is a clear relationship between Pacific phases and rainfall, it is far from uniform across the country.
For example, WA is mostly unaffected, while El Niño winters across the Murray-Darling Basin produce a substantial rain deficit averaging 42 per cent.
Complicating the impacts further, no two events are identical due to complex interactions with other drivers of variability, such as the Indian and Southern Oceans.
For example, the 2023 El Niño assisted in producing low winter and spring rain across Australia's east and south coast, while the south-east inland escaped with near-average falls, and northern Australia was mostly wet.
But El Niño affects much more than just rainfall; it also lays the background for:
- Above-average daytime temperatures.
- Increased extreme hot days in the warmer months.
- Higher fire danger for south-east states.
- Increased cool-season frost.
- Decreased alpine snowfall.
- A late start to the northern wet season and reduced cyclone numbers.
While the odds are greatly stacked in favour of the above outcomes, nothing is guaranteed.
Some El Niño years, like 1991, had bumper snow seasons, while 1997 winter maximums were not particularly warm.
Globally, El Niño brings a mixture of floods, droughts, hot and cold, but there is one constant — El Niño years, when averaged across the world, are typically hot, and the year that follows is frequently the hottest on record.
[CORE: ERA5 GRAPH]The graph above highlights the year following El Niño onset, with new global records occurring in 1941, 1958, 1973, 1998, 2016, and 2024, whereas record-high temperatures in the year of El Niño onset were observed in 2015 and 2023.
Dispelling the myths — what El Niño is and isn't
The most recent El Niño declaration in 2023 was followed by abundant misinformation, particularly a false perception that a hot and dry summer was likely, which, following widespread flooding, brought into question the BOM's credibility.
However, historical data show that, on average, summer rainfall decreases by a negligible 2 per cent.
Perhaps El Niño is associated with dry summers because summer precipitation during La Niña increases by an average of 29 per cent.
Or possibly it was the BOM's seasonal outlooks in early spring 2023, favouring below-normal summer rain, although by October their long-range forecasts showed an even money bet on a wetter or drier season.
Another myth is that El Niño (or La Niña) are forecasts when these are actually just terms used to describe the two sides of a naturally occurring oscillation in the Pacific — so while El Niño tips the scales to favour certain outcomes, it is far from a guarantee.
And finally, El Niño (and La Niña) events are global — you cannot have El Niño in Australia and La Niña in the Americas. It is one in, all in, a confusion that possibly arises from the variable consequences — Australia often sees drought, while other regions, like California and northern Mexico, have the dice loaded to favour rain and flooding.
