September 2026
A powerful El Niño is developing across the tropical Pacific.
The signal is now clear on satellite thermal imagery. A broad tongue of exceptionally warm surface water extends westward from the coast of South America across the equatorial Pacific. Beneath the surface, large volumes of anomalously warm water have accumulated, while atmospheric circulation across the Pacific has shifted into an El Niño configuration.
The World Meteorological Organization (WMO) reported on 3 September that El Niño is firmly established and expected to strengthen further, with an almost 100% probability that El Niño conditions will persist through to February 2027. The WMO warns that the event could become very strong, significantly altering rainfall and temperature patterns around the world.
For Australia, the implications are significant. But El Niño is not a weather forecast in itself. It changes the probabilities of drought, heat, fire, storms and rainfall — and those risks interact with other climate drivers and with conditions already present on the ground.
That distinction is important from a risk intelligence perspective.
Figure 1. Sea-surface temperature anomalies across the Pacific in August/September 2026. The strong band of anomalously warm water along the equatorial Pacific is characteristic of the developing El Niño. Source: Copernicus Marine Service.
What is happening in the Pacific?
El Niño is part of the El Niño–Southern Oscillation (ENSO), a coupled interaction between the tropical Pacific Ocean and the atmosphere.
During 2026 the transition has been unusually rapid. Earlier in the year the Pacific was emerging from weak La Niña conditions. By May, warming in the central and eastern tropical Pacific was sufficiently strong for the WMO to place the probability of El Niño during June–August at around 80%. By July, El Niño had developed and was strengthening rapidly.
By August the signal had become much stronger.
NOAA reported in its 13 August assessment that sea-surface temperature anomalies exceeded +2°C in parts of the eastern equatorial Pacific, while substantial anomalous warmth was also present below the surface. Its Niño-3.4 index for July was +1.4°C, while Niño-1+2, closer to South America, had reached +2.9°C.
The WMO’s September assessment goes further: El Niño is now firmly established, exceptionally warm tropical Pacific conditions are supporting further intensification, and a very strong event is possible during the coming months.
Figure 2. Sea-surface temperature anomalies during September 2026, showing intense warming in the eastern and central equatorial Pacific.
The significance extends far beyond the Pacific Ocean.
As warm water and tropical convection move eastward, they alter the enormous atmospheric circulation system above the Pacific. This can shift rainfall belts, jet streams and storm tracks thousands of kilometres away. NOAA describes the classic response as rainfall moving eastwards with the warm water, contributing to wetter conditions around parts of the eastern Pacific while increasing the tendency towards dryness over Indonesia and Australia.
The WMO’s September–November outlook consequently shows an increased likelihood of above-normal temperatures across almost all land regions, together with substantial shifts in rainfall patterns.
What are El Niño and La Niña?
El Niño and La Niña are opposite phases of the El Niño–Southern Oscillation (ENSO) — a recurring interaction between the tropical Pacific Ocean and atmosphere.
During El Niño, trade winds across the equatorial Pacific generally weaken. Warm surface water spreads eastwards towards the central and eastern Pacific, the thermocline deepens in the east, and cold nutrient-rich water is less effectively brought to the surface off South America. Tropical rainfall and atmospheric circulation consequently shift eastwards.
For Australia, El Niño is commonly associated with reduced winter and spring rainfall across eastern and northern Australia, warmer daytime temperatures and increased fire-weather risk in parts of the country.
During La Niña, the pattern is broadly reversed. Stronger trade winds push warm surface water towards the western Pacific. Cooler water rises more strongly in the eastern Pacific, while warm water and convection become concentrated closer to Australia and Indonesia.
La Niña therefore tends to increase the probability of above-average rainfall and flooding across eastern and northern Australia.
Neither phenomenon determines the weather by itself. ENSO interacts with the Indian Ocean Dipole (IOD), Southern Annular Mode (SAM), Madden–Julian Oscillation, local sea-surface temperatures and normal weather variability. Two El Niño events of similar strength can therefore produce very different impacts in Australia.
What could El Niño mean for Australia in 2026–27?
The Australian signal deserves careful interpretation.
The Bureau of Meteorology reported on 1 September that El Niño is firmly established, with both oceanic and atmospheric indicators consistent with a strong event, and further intensification likely during spring.
The Bureau’s latest long-range forecast, issued on 3 September, indicates that September–November rainfall is likely to be below average across parts of southern and eastern Australia, including southeastern Australia and Tasmania, as well as parts of Queensland and the northern Top End. At the same time, rainfall is expected to be above average across much of western Australia. Daytime temperatures are likely to be above average south of the tropics and overnight temperatures above average across most of the continent.
For southeastern Australia in particular, the combination of reduced rainfall, increasing temperatures and drying vegetation deserves attention as spring progresses into summer.
Historically, El Niño years have produced substantially reduced winter–spring rainfall across eastern Australia. The Bureau notes that nine of the ten driest winter–spring periods on record in eastern Australia occurred during El Niño years, while average winter–spring rainfall in the Murray–Darling Basin during El Niño events has been around 28% below the long-term average.
El Niño also tends to increase daytime temperatures. Reduced cloud cover can increase solar heating and evaporative demand, allowing soils and vegetation to dry more rapidly.
That can translate into greater bushfire risk.
The relationship, however, is not deterministic. Some severe Australian fire seasons have followed El Niño conditions, while others have not. The Bureau specifically cautions that the strength of El Niño in the Pacific does not necessarily translate directly into the strength of its impacts in Australia.
That uncertainty is central to understanding the risk.
1982–83: the precedent Australia should remember
There is an uncomfortable historical comparison.
The 1982–83 El Niño was one of the strongest events of the twentieth century, and its impacts demonstrated how a large-scale climate anomaly can cascade through environmental, agricultural, economic and disaster systems.
In Australia, rainfall began declining in April 1982.
The drought subsequently became extraordinary.
According to the Bureau of Meteorology, during the eleven months from April 1982 to February 1983, virtually the entire eastern two-thirds of Australia recorded rainfall within the driest 10% of historical observations. Large areas of Victoria, southern New South Wales and South Australia, and parts of Queensland experienced record-low rainfall for the period.
Figure 3. Percentage of total rainfall from April 1, 1982 to February 28, 1983 compared to 1991-2020 average total for the same months. Source: Australian Bureau of Meteorology.
Conditions became particularly dangerous during the summer of 1982–83.
Prolonged drought had dried forests and grasslands. Heatwave conditions then developed across southern Australia. On 16 February 1983 — Ash Wednesday — catastrophic bushfires swept across Victoria and South Australia.
The climatic conditions did not cause the individual ignitions, but they created an environment in which fire consequences could become extreme. The Bureau identifies the combination of El Niño and a positive Indian Ocean Dipole in 1982 as particularly important: both climate drivers favoured reduced rainfall across southeastern Australia, contributing to what became the driest year on record for the region.
Then, remarkably, the pattern changed.
In March 1983, flood rains arrived across central and southern Australia and were followed by several months of above-average rainfall.
This is an important lesson in its own right: climate risk can change rapidly from one hazard regime to another.
Drought does not eliminate flood risk. Fire does not eliminate subsequent storm risk. Risk management therefore needs to consider transitions and compound hazards rather than treating each hazard independently.
The 1982–83 El Niño was a global disaster
Australia was only part of the story.
Across the Pacific, the atmospheric circulation changed dramatically. Ecuador and northern Peru experienced exceptional rainfall and major flooding. NOAA records rainfall of up to approximately 100 inches — around 2.5 metres — in some locations over six months. Indonesia and Australia experienced severe drought and fires.
The warm eastern Pacific also disrupted marine ecosystems and fisheries by suppressing the normal upwelling of cold, nutrient-rich water along the South American coast.
French Polynesia experienced extraordinary tropical cyclone activity. Other regions experienced major disruptions to rainfall, agriculture and water availability. Contemporary NOAA assessments put global economic losses associated with the 1982–83 event at more than US$8 billion — an enormous figure at the time.
El Niño therefore illustrates an important feature of modern disaster risk:
one physical climate driver can generate many different hazards in many different places at the same time.
2026 is not 1982: the rise of risk intelligence
There is, however, one fundamental difference between 1982 and today.
We can see much more of the risk developing.
The emerging 2026 El Niño has been observed from space, measured by ocean buoys and floats, detected below the ocean surface, assimilated into global climate models and compared across multiple forecasting systems.
Modern observing systems continuously measure sea-surface temperature, subsurface ocean heat, atmospheric pressure, winds, rainfall, soil moisture, vegetation condition and many other variables.
The Bureau’s ACCESS-S seasonal forecasting system, for example, incorporates millions of observations from satellites, terrestrial stations and ocean instruments to simulate the evolution of the atmosphere and oceans months ahead.
The WMO notes that modern seasonal forecasting systems can provide useful indications of climate patterns one to six months in advance, giving governments and organisations time to prepare for drought, heavy rainfall and associated consequences.
This represents more than improved weather forecasting.
It is increasingly a form of risk intelligence.
From forecasting the climate to forecasting consequences
Knowing that El Niño is developing is useful.
Knowing what it could affect, where, when and with what consequences is much more valuable.
A modern risk-intelligence system can combine climate forecasts with information about:
- soil moisture and vegetation dryness;
- fuel loads and fire behaviour;
- reservoir and water-storage levels;
- crop conditions and agricultural exposure;
- electricity demand and network vulnerability;
- transport and telecommunications infrastructure;
- ecosystem stress;
- health and heatwave vulnerability;
- insurance exposure;
- supply chains; and
- emergency-service capacity.
This transforms a statement such as:
“A strong El Niño is developing”
into questions that decision-makers can act upon:
Where is drought risk increasing?
Which catchments and communities have the least resilience if rainfall fails?
Where are fuel loads likely to become dangerous by summer?
Which electricity transmission assets are exposed to simultaneous extreme heat and bushfire?
Where could water shortages affect agriculture, industry or towns?
Which regions could experience the opposite problem — extreme rainfall or flooding?
This is the transition from hazard monitoring to integrated risk intelligence.
Early warning creates something extremely valuable: time
The developing 2026 event demonstrates why this matters.
In May, international forecasting centres were already identifying a rapidly increasing probability of El Niño. By July, the event had developed. By August, observations showed substantial intensification. At the beginning of September, the WMO was warning governments to prepare for the possibility of a very strong event extending into 2027.
That progression provides months of potential warning.
For governments, utilities, agricultural businesses, insurers and emergency-management agencies, those months can be used to inspect critical infrastructure, review water availability, reassess bushfire preparedness, identify vulnerable populations, pre-position resources and stress-test contingency plans.
The purpose of forecasting is therefore not simply to predict an event correctly.
The purpose is to create decision time.
And the value of that information increases when forecasts are integrated with exposure, vulnerability and consequence data.
But there are still major unknowns
Better information should not be confused with certainty.
Even with one of the world’s most intensively observed climate systems, substantial uncertainties remain.
We do not yet know exactly how strong the 2026–27 El Niño will become. More importantly, its ultimate strength will not tell us precisely what will happen in any particular Australian region.
Other climate drivers matter.
The WMO expects a positive Indian Ocean Dipole to develop during 2026, while the Bureau continues to monitor the interaction between the Pacific, Indian Ocean and Southern Ocean. Local ocean temperatures, soil moisture, synoptic weather systems and the Southern Annular Mode can all amplify or counteract the typical El Niño signal.
The background climate is also different from 1982.
Global and regional sea-surface temperatures are exceptionally warm. Australia’s surrounding oceans contain areas of unusually warm water. That can modify atmospheric moisture, rainfall and temperature responses in ways that make simple historical analogues unreliable.
And the historical record itself provides an important warning against overconfidence.
The very strong 1997–98 El Niño did not produce Australian rainfall impacts proportional to its extraordinary Pacific strength, whereas weaker El Niño events have sometimes produced severe Australian drought.
So 1982–83 is a precedent.
It is not a prediction of 2026–27.
The real lesson from 1983
The lesson from the 1982–83 El Niño is not that Australia should expect another Ash Wednesday.
It is that climate anomalies can create cascading and interacting risks.
Rainfall deficits can become soil-moisture deficits.
Soil-moisture deficits can become agricultural drought.
Drought and heat can increase vegetation stress and fire danger.
Extreme heat can simultaneously increase electricity demand, reduce the performance of some infrastructure and threaten human health.
A fire can then disrupt electricity networks, telecommunications and transport corridors.
And eventually the climate regime can change again — potentially replacing drought and fire risk with intense rainfall and flooding.
Risk does not sit neatly inside individual hazard categories.
That is why the emergence of modern risk intelligence is so important.
Satellites, ocean observations, climate models, environmental sensors and increasingly sophisticated data analytics mean that we are entering the 2026–27 El Niño with vastly greater situational awareness than was possible in 1982.
But information alone does not make society resilient.
The critical step is connecting that information to exposure, vulnerability, consequences and decisions.
Watching the Pacific — and preparing for uncertainty
The enormous band of warm water now visible across the equatorial Pacific is a reminder of the scale of the Earth systems that influence Australian risk.
We cannot prevent El Niño.
Nor can we predict precisely how every consequence will unfold.
But we can observe its development earlier, model possible consequences, identify vulnerabilities before they become disasters and continuously update our assessment as new information arrives.
That is ultimately what risk intelligence should provide:
not certainty about the future, but enough warning and understanding to make better decisions before the consequences arrive.
For Australia, the next several months will provide an important test of that capability.
