While parts of Asia contend with extraordinary rain, flooding and tropical storms, changes taking place across the Pacific Ocean could have almost the opposite consequence for Australia.

El Niño is one of the most important influences on Australian weather.

It does not determine whether it will rain tomorrow, nor does it guarantee drought or bushfires.

But it changes the odds.

And with El Niño conditions now established in the Pacific and indications that the event may strengthen, Australians have good reason to understand what it is — and what it could mean as the country moves towards spring and summer.

What is El Niño?

El Niño is the warm phase of a natural Pacific climate cycle known as the El Niño–Southern Oscillation, or ENSO.

Under more normal conditions, trade winds push warm surface water westwards across the tropical Pacific towards Australia and South-East Asia.

During El Niño, those trade winds weaken and unusually warm water develops farther east across the central and eastern equatorial Pacific.

That apparently remote change in ocean temperature can reorganise atmospheric circulation across an enormous area.

Clouds, rainfall and tropical convection tend to move farther east across the Pacific.

For Australia, that can mean less moisture arriving from the Pacific and a greater likelihood of dry conditions.

The Bureau of Meteorology says typical Australian El Niño effects can include reduced rainfall in eastern Australia, warmer daytime temperatures, greater extreme-heat risk, increased fire danger in the southeast, reduced alpine snow, increased frost risk and a later start to northern Australia's wet season.

Every El Niño, however, is different.

What is happening now?

The Pacific is already displaying El Niño characteristics and climate agencies are watching its development closely.

The significance for Australia is not simply what the Pacific looks like today, but how the ocean-atmosphere system develops during the remainder of winter and through spring.

There are indications elsewhere in the Asia-Pacific region that the broader weather system is becoming particularly active.

The Philippines has recently experienced substantial monsoonal rain, flooding and landslides, while Typhoon Dolphin has contributed to an extraordinary period of weather extending through parts of East Asia.

China has also experienced exceptional rainfall and serious flooding associated with Dolphin.

It would be misleading, however, to attribute individual storms or the current Philippine rainfall directly to El Niño.

Tropical cyclones, local weather systems and the southwest monsoon are the immediate drivers.

El Niño operates differently: it changes the large-scale background conditions in which weather systems develop.

That distinction matters.

How can the Philippines be wet if El Niño can make Australia dry?

It sounds contradictory.

It isn't.

El Niño does not simply make the entire western Pacific dry.

It changes atmospheric circulation, ocean temperatures, winds and the geographical distribution of tropical rainfall.

Individual tropical cyclones can still produce enormous quantities of rain.

Monsoonal systems can still cause floods.

Indeed, changing Pacific conditions can alter tropical cyclone tracks and behaviour in complicated ways.

Consequently, Australians should not look at television pictures of flooding elsewhere in Asia and conclude that a wet Australian season must follow.

The Australian consequences can be very different.

Australia could be heading towards a drying period

Historically, one of the clearest El Niño signals in Australia has been reduced winter and spring rainfall, particularly across eastern and northern Australia.

The Bureau notes that nine of the ten driest winter–spring periods recorded in eastern Australia occurred during El Niño years.

Across the Murray–Darling Basin, average winter–spring rainfall during El Niño events since 1900 has historically been substantially below the long-term average.

That does not mean drought is inevitable in 2026.

It means the probability of dry conditions increases.

That distinction is important when discussing seasonal climate forecasts.

Farmers will be watching closely

For Australian agriculture, rainfall arriving — or failing to arrive — at the right time can be more important than the annual rainfall total.

A dry spring can affect pasture growth, winter crops, water availability and livestock decisions.

Higher temperatures can simultaneously increase evaporation from soil and dams.

The combination can therefore be more damaging than simply receiving fewer millimetres of rain.

Farm businesses across eastern Australia will consequently be watching both rainfall forecasts and soil-moisture conditions closely as spring approaches.

It could become hotter

El Niño is also associated with warmer daytime temperatures across much of Australia, particularly through the southern two-thirds of the continent.

Reduced cloud cover allows more solar heating during the day.

When that occurs alongside declining soil moisture, temperatures can rise further because less energy is being consumed through evaporation from wet landscapes.

Australia can therefore experience the double effect of less rainfall and greater drying.

That becomes increasingly important as summer approaches.

Bushfire risk becomes part of the story

Dry vegetation does not automatically produce catastrophic bushfires.

Fire requires ignition and suitable weather conditions.

But El Niño can help establish the background conditions that make serious fire weather more likely.

Reduced rainfall, warmer temperatures and declining soil moisture can progressively dry forests and grasslands.

The Bureau says significant fire-danger seasons in southeastern Australia are more likely following El Niño conditions, particularly when other climate drivers reinforce the drying influence.

That makes conditions during the coming spring particularly important.

If substantial rain continues to fall, the landscape may retain moisture.

If rainfall declines sharply while temperatures increase, fuel can progressively dry.

Northern Australia faces a different consequence

El Niño can also affect northern Australia's wet season.

Rather than necessarily producing an immediate dramatic drought, it can delay the arrival of the monsoon and the first substantial wet-season rains.

El Niño years are also generally associated with fewer tropical cyclones around Australia.

Fewer cyclones, however, does not mean there is no cyclone risk.

One severe cyclone can obviously have enormous consequences.

It is a change in probability rather than an assurance of safety.

Even Australia's snowfields can be affected

El Niño's influence extends into the Australian Alps.

Historically, El Niño years have tended to produce lower snow depths and shorter snow seasons.

The Bureau has previously calculated that average peak snow depth at Spencer's Creek in the Snowy Mountains is around 35 centimetres lower during El Niño years, while the period with snow deeper than one metre is about two and a half weeks shorter.

For alpine tourism operators, the Pacific Ocean can therefore have a surprisingly direct commercial consequence.

There can also be an economic effect

Weather eventually becomes economics.

A sufficiently dry El Niño period can affect agricultural production.

Lower production can influence food prices.

Low inflows can reduce water availability.

Hot weather increases electricity demand for cooling.

Bushfires can affect tourism, insurance claims, transport and communities.

Poor snow seasons affect alpine businesses.

And reduced rainfall can place additional pressure on rural communities already dealing with high fuel, fertiliser, machinery and financing costs.

The consequences therefore extend well beyond the weather forecast.

Does El Niño mean Australia will have a drought?

No.

This is perhaps the most important qualification.

El Niño increases the likelihood of particular conditions but does not dictate Australia's weather.

Other climate influences matter, including Indian Ocean temperatures, the Southern Annular Mode, local sea temperatures and individual weather systems.

Some strong El Niño events have produced surprisingly limited rainfall effects in parts of Australia, while weaker events have coincided with serious drought.

Weather does not follow a single switch.

El Niño changes the probabilities.

What Australians should watch now

The critical period will be the transition from winter into spring.

Rainfall during that period will help determine soil moisture, crop prospects, dam inflows and how quickly vegetation dries before summer.

Australians should consequently watch more than the declaration that an El Niño exists.

The important indicators will be whether it strengthens, how long it persists, what happens to Australia's winter and spring rainfall, and whether other major climate drivers reinforce or counteract its influence.

Pictures of torrential rain and flooded streets elsewhere in the Asia-Pacific may make a drying Australia seem improbable.

The Pacific climate system is considerably more complicated than that.

The same vast ocean-atmosphere system can contribute to very different weather outcomes thousands of kilometres apart.

The Times View

El Niño is not a forecast that Australia will experience drought, heatwaves or bushfires.

It is a warning that the climatic odds are changing.

For Australia, the greatest significance may emerge gradually: less rain through important agricultural regions, warmer days, drying vegetation, reduced water inflows and potentially greater fire danger as summer approaches.

The rain currently falling elsewhere in Asia should not provide Australians with false reassurance.

The weather event worth watching is not a single storm.

It is what is happening across the Pacific — and what that could mean for Australia during the months ahead.