What is Godzilla El Niño?

You may have heard the rumours of a “monster El Niño”. It’s not the first time we’ve heard forecasts like this in Australia, but this time they are not coming out of nowhere.

Early signs in the Pacific have been building for months and forecasts now point to a high likelihood of a moderate to strong El Niño developing in 2026.

But even so, a big El Niño does not necessarily mean a big dry for Australia.

Earlier this year, the World Meteorological Organization confirmed what many climate scientists had been watching closely: warm ocean waters are feeding the system, the atmosphere is beginning to respond, and forecast models are increasingly aligned.

This is no longer a weak signal. An El Niño is now likely and it could become strong. But that does not automatically make its impacts straightforward.

What is El Niño?

El Niño, part of the El Niño-Southern Oscillation (ENSO), matters because it reorganises the climate system.

The event begins with warming in the tropical Pacific Ocean. Trade winds weaken, upwelling slows along the equatorial Pacific, and rainfall systems shift toward warmer waters. These changes alter major atmospheric circulation patterns and redistribute rainfall and temperature across large parts of the globe.

The vast amount of heat stored in the tropical Pacific can also influence global temperatures by transferring additional heat from the ocean into the atmosphere.

The most recent El Niño of 2023-24 was among the strongest observed in recent decades and contributed to exceptionally warm global temperatures.

Even moderate El Niño events can increase the likelihood of heatwaves, floods and droughts in different regions of the world, while stronger events may amplify these risks further.

But in Australia, the story is different

In Australia, El Niño is often associated with drier-than-average conditions, particularly across eastern parts of the country. As soon as talk of a “monster El Niño” emerges, concerns about drought tend to follow.

There are good reasons for that concern.

The Millennium Drought coincided with several El Niño events, while the 1982-83 El Niño remains one of the most notable drought-associated events in Australia’s recent climate history.

However, averages only tell part of the story.

When individual El Niño events are examined, the relationship between El Niño strength and Australian rainfall becomes much less tidy. Some El Niño events coincide with severe dryness, while others do not. Some of the strongest El Niño events on record produced rainfall that was close to average across large parts of Australia.

Apart from some regions of southeastern Australia, departures from average conditions are often relatively modest rather than extreme.

This is where the story becomes more nuanced than many headlines suggest.

There is a strong temptation to think of El Niño as a simple dial where stronger events automatically lead to more severe drought. But for Australia, the evidence does not support such a simple relationship.

Looking across historical events reveals no clear connection between El Niño strength and Australian rainfall outcomes. Strong El Niño events make for compelling headlines but often prove to be poor rainfall predictors.

What should Australians take from this?

A moderate to strong El Niño is now likely. That is important and it is worth paying attention to.

But a “mega” El Niño does not automatically translate into “mega” dry conditions.

Modern seasonal forecast systems provide a much better guide to likely conditions because they simulate the full climate system, including interactions between the ocean, atmosphere and land surface. These models capture complexity that simple El Niño narratives miss.