Australia faces rising heat risks, uneven rainfall and mounting pressure
to prepare for a hotter climate
| Key Points |
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Across the tropics, ocean temperatures and winds are shifting into a powerful El Niño.
The Bureau of Meteorology says the developing event could exceed previous records in the strength of its central Pacific warming.
That prospect raises serious questions about Australia's approaching summer and the risks facing communities already exposed to extreme heat.
El Niño forms when surface waters in the central and eastern equatorial Pacific become unusually warm. Easterly trade winds weaken, allowing warm water to spread eastwards.
The distribution of tropical rainfall changes, disrupting atmospheric circulation far beyond the Pacific.
Scientists describe the wider cycle as the El Niño–Southern Oscillation, or ENSO. Its three phases are El Niño, neutral conditions and La Niña.
During El Niño, the Walker circulation, a large-scale atmospheric system linking rising and sinking air across the tropical Pacific, weakens and shifts.
Rainfall that normally favours the western Pacific can move towards the central and eastern Pacific. Australia consequently faces a greater risk of dry conditions in some regions, particularly during winter and spring. La Niña generally produces the opposite Pacific temperature pattern and often favours wetter conditions across eastern and northern Australia.[1]
The name El Niño originated with Peruvian fishermen, who noticed the seasonal appearance of warmer coastal waters around Christmas. The term means “the boy” in Spanish and traditionally referred to the Christ child.
Scientists monitor sea surface temperatures across defined sections of the tropical Pacific. The Oceanic Niño Index, or ONI, measures three-month average temperature departures in the Niño 3.4 region. The US National Oceanic and Atmospheric Administration uses this measure, alongside atmospheric evidence, to classify El Niño and La Niña episodes.
Temperature readings alone do not tell the whole story. Scientists also examine trade winds, atmospheric pressure, cloud patterns and the Southern Oscillation Index. Together, these observations reveal whether the ocean and atmosphere are reinforcing each other.
Descriptions such as “Super El Niño” commonly refer to an exceptionally strong event, but they are not formal categories used by the Australian Bureau of Meteorology. The Bureau's September assessment said models indicated the developing event could exceed the previous central Pacific sea surface temperature record, established during the 1982–83 event.[2]
Forecasts nevertheless carry uncertainty. Ocean and atmospheric conditions can evolve differently from model projections, particularly when predictions extend months into the future.
El Niño often reduces rainfall across parts of eastern and southern Australia while increasing the likelihood of above-average temperatures. Lower soil moisture, clearer skies and prolonged dry spells can place pressure on agriculture, reservoirs and ecosystems.
But Australia does not respond uniformly to Pacific warming. The Bureau's October outlook points to above-average temperatures across much of the continent, while rainfall prospects differ sharply by region. Parts of south-eastern Australia face a greater chance of below-average rainfall, while many western and central areas have a stronger wet signal.[3]
Other climate influences can reinforce or counter the El Niño signal. The Indian Ocean Dipole, Southern Annular Mode, local ocean temperatures and passing weather systems all influence the eventual outcome.
The 2023–24 El Niño illustrates the complexity. Australia experienced exceptionally dry conditions during August to October 2023, but later east coast storms and tropical cyclones brought substantial rainfall to widespread areas. The Bureau attributes those outcomes to several interacting climate influences, not El Niño alone.[1]
For farmers, emergency services and water managers, regional forecasts therefore matter more than dramatic descriptions of the event's strength.
El Niño can increase the likelihood of hot conditions, particularly where reduced rainfall dries vegetation and soil. Dry fuel, strong winds and extreme temperatures can combine to produce dangerous fire weather. The relationship is not automatic, however, and individual fires depend on local conditions and ignition sources.
Climate change adds another layer of risk. Human-driven greenhouse gas emissions have raised global temperatures, increasing the likelihood and intensity of many heat extremes. An El Niño event operates within that warmer background rather than replacing it.
The distinction matters for emergency planning. Authorities cannot assume every El Niño will produce a repeat of 2019–20, nor can they dismiss the possibility of severe fire seasons when forecasts appear mixed.
Heat also creates risks beyond bushfires. Hotter days and nights can threaten older people, outdoor workers, people without reliable cooling and households already struggling with energy bills. Hospitals, electricity networks and emergency services must prepare for periods of sustained demand.[4]
The consequences extend far beyond Australia. El Niño can bring drought to parts of Indonesia and southern Africa while increasing rainfall and flood risks in parts of the Americas. The precise pattern varies between events.
Farmers can face simultaneous challenges: water shortages in one region, excessive rain in another and rising costs for irrigation, transport or imported food. Poor harvests in major producing countries can influence international commodity prices, although markets also respond to wars, trade restrictions, storage levels and demand.
Marine ecosystems face their own disruption. Along the Pacific coast of South America, weakened trade winds reduce the upwelling of cold, nutrient-rich water. That can diminish food supplies for plankton, fish and seabirds, placing pressure on fisheries that support coastal communities.
Warmer ocean conditions also influence coral reefs and marine heat stress. Yet El Niño does not account for every marine disturbance. Long-term ocean warming, pollution and overfishing can compound the damage.[5]
El Niño can contribute to higher coastal water levels and damaging waves in parts of the Americas, especially along the Pacific coast. Warmer water expands, while altered winds, currents and storms can affect local sea levels and coastal flooding.
Scientists must distinguish these temporary regional effects from long-term global sea-level rise. Human-caused warming drives sustained ocean expansion and land-ice loss, raising the baseline on which tides and storm surges act.
A powerful El Niño may worsen particular coastal hazards, but it does not independently explain every flood. Local geography, storm tracks, tides and coastal protection determine the damage at individual sites.[5]
Australia cannot control the Pacific climate cycle. It can improve its response to the risks that forecasts identify. Farmers need timely regional advice, water authorities need credible demand and supply projections, and emergency services need plans for heatwaves and dangerous fire weather.
Governments must also address the longer-term causes of rising heat. Reducing greenhouse gas emissions will not stop El Niño, but it can limit the additional warming that makes many extremes more dangerous. Adaptation and emissions reduction serve different purposes, and Australia needs both.
The developing event deserves close attention, not sensationalism. Its strength is scientifically significant, but the consequences will depend on how ocean conditions interact with Australia's varied climate, the wider atmosphere and the warming already caused by human activity.
For communities facing the coming summer, the useful question is not whether the Pacific sets a record. It is whether decision-makers use the warning to protect people, farms, ecosystems and essential services before the next extreme arrives.
- Bureau of Meteorology, El Niño and La Niña.
- Bureau of Meteorology, El Niño strength doesn't always match impact on Australia, updated September 2026.
- Bureau of Meteorology, Climate outlook for October to January, September 2026.
- Bureau of Meteorology, El Niño: what it means for Australia's climate.
- World Resources Institute, Super El Niño impacts explained.
- National Oceanic and Atmospheric Administration, El Niño Theme Page FAQ.
- World Meteorological Organization, El Niño and La Niña phenomena.
- National Oceanic and Atmospheric Administration, What are El Niño and La Niña?.
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