El Niño Declared in Australia, Climate Change Complicates Predictions

As Australians brace for the second half of 2026 to be influenced by El Niño, scientists are warning that the impacts of the weather pattern are becoming harder to predict due to climate change.

The Bureau of Meteorology has officially declared an El Niño active in Australia, which refers to an extended period of warmer-than-usual water in the central and eastern Pacific.

It is the first time such a declaration has been made in almost three years and means much of the country is set to experience hotter and drier conditions over the coming months.

Modelling suggests this El Niño could become the strongest on record, but that does not necessarily mean Australia will experience record heat and drought.

Monash University adjunct professor and climate councillor Andrew Watkins said this event coincided with global temperatures increasing by about 1.5 degrees Celsius.

"With climate change, we've already boosted the risk of heat and fire weather and drought and even marine heat waves and coral bleaching," he said.

"El Niño adds to all of those, so increases the risk even further of having heat, drought, fire weather and coral bleaching as well.

Dr Watkins said scientists could still predict when El Niño and the cooler, wetter La Niña were likely to develop, but climate change was making their effects harder to forecast.

"We now have more moisture in the atmosphere for each degree of global warming," he said.

"With El Niño, long dry periods, cloudless skies, but when that weather does come that can bring a bit of rain. It could bring more rain than normal."

UNSW climate scientist Andrea Taschetto said research suggested El Niño and La Niña events could become more regular and intense, but the data record was short.

"The fact that we have a warmer atmosphere with more moisture in the atmosphere, that means that the impact of El Niño can be different than it has been in the past," she said.

"Climate models in the future project that there is an intensification of El Niño and La Niña in the future, which might have a stronger impact in the future for us."

How will this affect Australia?

El Niño typically brings drier conditions to central and eastern Australia in winter and spring.

"El Niño is a cruel system. It tends to give us a burst of rain just as it's developing … then the drought sets in," University of Queensland emeritus professor of climate science Roger Stone said.

The Bureau of Meteorology's long-range forecast suggests rainfall is likely to be below average across parts of southern and eastern Australia from July to September.

The whole country is facing above-average overnight temperatures and everywhere, apart from northern Australia, can expect higher-than-usual daytime temperatures over coming months.

Dr Taschetto said the forecast was consistent with what was typically seen during an El Niño.

"A drier spring, which is the time when El Niño has a stronger influence on Australian rainfall and warmer days and nights," she said.

Professor Stone said recent cutbacks to monitoring systems run by the United States's National Oceanic and Atmospheric Administration had made it harder to track how this El Niño was developing.

"There's been a cutback in measurement systems over the last couple of years," he said.

Australia's weather is also shaped by other climate factors, meaning outcomes can vary.

Much of the country is experiencing a wet month, which is being influenced by conditions in the Indian and the Southern Ocean, as well as local water temperatures.

The last El Niño, which developed in 2023, saw Australia's driest three-month period on record between August and October, but it was also influenced by a strong positive Indian Ocean Dipole.

"It's not only about El Niño, but it's also what is happening in the atmosphere in terms of lows and highs that produces the weather that we feel on the ground," Dr Taschetto said.

The 2025/26 summer heatwave happened against the backdrop of weak La Niña conditions, the cooler and wetter counterpart to the El Niño.

Strong El Niño

Modelling suggests that this year's El Niño could become the strongest in the modern era, with warming in the Pacific possibly exceeding 3 degrees Celsius.

But Professor Stone said the strength of El Niño was not always proportional to impacts.

"The last really super El Niño of the century was only three years ago … it had absolutely no effect on most of Australia — perhaps a bit around Perth and the north-west of Western Australia," he said.

"It dried out the Indian Ocean, of all things, Cocos Islands, Bali, places like that, but had very little effect on Australia."

Professor Stone said prolonged droughts, such as those between 1991 and 1995 as well as the Millennium Drought, were historically linked to moderate El Niño.

"The way the Pacific behaves and the way the atmosphere behaves, it doesn't necessarily mean the warmer the sea temperatures are in the central Pacific, the worse the droughts are in Australia," he said.

"It's a system where the change in the atmosphere over the Pacific changes the circulation patterns over Australia and that then decides whether we're going to have a severe drought or not."