Each time we see an El Niño event, it has led to periods of hotter and drier conditions.
Once again, the Pacific is warming in ways that have long shaped the fate of harvests, forests, and water supplies across Australia's eastern reaches. The Bureau of Meteorology and the World Meteorological Organization now agree with unusual clarity: El Niño is returning, carrying a 90 percent probability of forming before November — the first such event since 2023. History offers a sobering frame, with nine of the ten driest winter-spring periods on record tied to El Niño years, and climate change standing ready to deepen whatever hardship the pattern brings.
- Models from agencies around the world are converging on the same signal — El Niño is forming in the Pacific, and Australia's east is in its path.
- The historical record is unsparing: El Niño years have dominated the list of Australia's driest winters and springs, and this event is expected to reach at least moderate strength.
- Climate change is not a passive backdrop — it is actively amplifying the risks, turning dry spells drier, heat more extreme, and bushfire seasons more dangerous.
- Forecasters caution that strength alone does not determine impact; other climate drivers like the Indian Ocean dipole will shape what actually unfolds on the ground.
- The window of greatest vulnerability runs through winter and spring, giving communities, land managers, and emergency services a narrow but real runway to prepare.
Australia is preparing for the return of El Niño this winter — the first since spring 2023 — after the Bureau of Meteorology and international agencies converged on a forecast that carries a 90 percent probability of the event forming in the Pacific before November. Senior BoM climatologist Felicity Gamble described the alignment of predictive models as unusually clear, noting that the event is expected to reach at least moderate strength, with the possibility of becoming strong.
El Niño works by raising sea surface temperatures in the central equatorial Pacific, reshaping how air circulates globally and drawing moisture away from northern Australia. Historically, the pattern has been punishing: nine of the ten driest winter and spring periods on record have fallen during El Niño years, and the phenomenon elevates the risk of drought, heatwaves, bushfires, and coral bleaching. Gamble was careful to note, however, that the atmospheric response is still developing and that other climate drivers — including the Indian Ocean dipole and the southern annular mode — will also determine what conditions actually materialise. "An El Niño doesn't necessarily mean we switch overnight into drought conditions," she said.
The concern is sharpened by climate change. Dr. Andrew Watkins, a former head of climate prediction at the BoM, described the combination as "a very dangerous double act." Warming has already pushed Australia toward more frequent droughts and more days of dangerous fire weather; El Niño arriving on top of that shifted baseline intensifies the risk further. The pattern is also changing in character — dry periods are becoming exceptionally dry, and when rain does fall, it tends to arrive in downpours rather than steady precipitation.
El Niño's grip on Australian weather is strongest during winter and spring before weakening as summer approaches, a timing that gives planners a defined but limited window to act. Globally, the event is expected to bring extreme rainfall to parts of the Americas and weaken monsoons across South Asia — but for Australia, the immediate question is what the coming months will bring to an already stressed landscape.
Australia is bracing for the arrival of El Niño this winter—the first such event since spring 2023—after the Bureau of Meteorology and international agencies aligned their forecasts around a phenomenon that has historically meant hotter, drier conditions across the eastern half of the country.
The World Meteorological Organization put a number on the likelihood: a 90 percent chance that El Niño will develop in the Pacific before November. Felicity Gamble, a senior climatologist at the BoM, described the convergence of predictive models as unusually clear. "The models are really aligning now," she said. "We are expecting a transition to El Niño sometime during winter." The BoM's own analysis suggests the event will reach at least moderate strength, with the possibility it could become strong.
El Niño is the warm phase of a larger climate oscillation that shapes weather patterns across the globe. When it takes hold, sea surface temperatures in the central equatorial Pacific rise above their historical average, which shifts how air circulates around the planet. The result is less moisture in the atmosphere over northern Australia, while rainfall patterns migrate eastward toward the central and eastern Pacific. Gamble cautioned, however, that the atmospheric response is still developing. "We are seeing signs of that, but we're not quite there yet," she said.
For Australia, the historical record is sobering. Nine of the ten driest winter and spring periods on record have occurred during El Niño years. The phenomenon tends to push temperatures above average across much of the south, and it carries an elevated risk of drought, heatwaves, bushfires, and coral bleaching. Yet Gamble emphasized that the strength of an El Niño event does not automatically translate into proportional impacts on Australian weather. Other climate patterns—the Indian Ocean dipole and the southern annular mode among them—also shape what actually happens on the ground. "An El Niño doesn't necessarily mean we switch overnight into drought conditions," she said. "It's a more nuanced story."
The window of vulnerability is not uniform across the year. El Niño's influence on Australia peaks during winter and spring, then recedes significantly as summer approaches—a pattern that distinguishes it from its counterpart, La Niña. This timing matters for planning and preparation.
Dr. Andrew Watkins, a former head of climate prediction at the BoM and current Climate Councillor, framed the coming months in starker terms. "Climate change and El Niño are a very dangerous double act," he said. Climate change is already pushing Australia toward more frequent droughts, more days of dangerous bushfire weather, and more extreme heat. El Niño, arriving on top of that baseline shift, amplifies the risk. Watkins noted that while the strength of an El Niño—measured by how far above normal the Pacific temperatures climb—does not automatically guarantee proportional impacts in Australia, the historical pattern is consistent: each El Niño event has brought periods of hotter and drier conditions.
Climate change itself is altering how variability plays out. Rather than simply shifting the average, warming is intensifying extremes. Dry periods become exceptionally dry. When conditions favor rainfall, the result is often downpours rather than steady precipitation. Models compiled by the Columbia Climate School show wide disagreement on the precise magnitude of Pacific warming, but near-universal agreement that El Niño will form. Globally, the phenomenon can trigger extreme rainfall and flooding in the southern United States and Central America, and weaken monsoons across the Indian subcontinent. For Australia, the immediate concern is what winter and spring will bring.
Citações Notáveis
The models are really aligning now. We are expecting a transition to El Niño sometime during winter.— Felicity Gamble, senior BoM climatologist
Climate change and El Niño are a very dangerous double act. Climate change is already pushing us to more time in drought, more bushfire weather and extreme heat.— Dr. Andrew Watkins, Climate Councillor and former BoM climate prediction head
A Conversa do Hearth Outra perspectiva sobre a história
Why does the strength of El Niño not always match the strength of its effects in Australia?
Because Australia's weather is shaped by multiple systems at once. El Niño is powerful, but it's not the only thing in the room. The Indian Ocean dipole, the southern annular mode—these other patterns can either amplify or dampen what El Niño does. It's like having several instruments playing at once; the loudest one doesn't always determine the song.
So a strong El Niño could arrive and Australia might barely notice?
Not barely. But yes, the impacts could be less severe than the raw strength of the event would suggest. Conversely, a moderate El Niño hitting at the wrong moment, with other patterns aligned against us, could feel worse than expected. That's why forecasters are careful not to promise a direct equation.
You mentioned the timing—winter and spring are the vulnerable months. Why does El Niño's grip loosen in summer?
The seasonal dynamics of the atmosphere change. El Niño's mechanism relies on certain atmospheric circulation patterns that are strongest in the cooler months. Come summer, those patterns weaken naturally, and El Niño's leverage over Australian weather diminishes. It's still there, but it's not steering the ship anymore.
What does it mean that climate change is "pumping up" variability?
It means the baseline is shifting, and the swings are getting wider. A dry period in the old climate might have meant a 10 percent rainfall deficit. Now, the same atmospheric setup produces a 20 or 30 percent deficit. The extremes are getting more extreme. El Niño arriving in a warming world is not the same as El Niño arriving in the climate we had twenty years ago.
Is there anything that could prevent this El Niño from developing?
The models are aligned, and the Pacific is already warming. At this point, the probability is high enough that preparation is the sensible move. The question isn't whether it will happen, but how severe it will be and how other climate patterns will interact with it.