A dry outlook for eastern Australia over the next three months and talk of a possible strong or “super” El Nino is generating unease about drought and fire risks, but the Bureau of Meteorology cautions many factors are at play.

When it comes to El Nino, it’s still early days, every event differs and the strength doesn’t always match impacts on Australian weather, the bureau says on its website.

“Sometimes a weak El Nino can lead to significant impacts on Australia’s rainfall and temperature, while a stronger event may have fewer noticeable impacts.”

In 2023, an El Nino coincided with an Indian Ocean dry weather climate driver to help produce Australia’s driest three-month period on record, from August to October. But El Ninos typically have less influence during summer than in spring. East coast storms arrived in December to March and four tropical cyclones brought above-average rainfall.

Event declarations reflect ocean temperatures in the eastern Pacific and atmospheric patterns, while global meteorological organisations differ in their assessments and thresholds. The bureau doesn’t move in lockstep with northern hemisphere counterparts.

El Ninos have different impacts around the world.

The World Meteorological Organisation says an El Nino is typically associated with increased rainfall in parts of southern South America, the southern US, the Horn of Africa and central Asia, and drought over Australia, Indonesia and parts of southern Asia.

The WMO also cautions about the poor predictability of forecasts in April and says its update in late May will provide more robust guidance.

University of Melbourne postdoctoral research fellow in atmospheric sciences Kimberley Reid says on The Conversation that the phrase “super El Nino” makes climate scientists roll their eyes, and for Australia what matters more is whether El Nino is present or not.

The strength measure refers to ocean temperatures in the eastern Pacific, but that figure is not well correlated with less rain in eastern Australia and doesn’t reflect the atmospheric changes that influence the weather systems that actually bring rain here, she says.

It’s also too early to say anything other than that an El Nino is more likely to form this year than a La Nina.

“The current gold standard for Australian seasonal forecasts are the Bureau of Meteorology’s long-range forecasts,” she says. “But even here, these forecasts become quite uncertain more than a month in the future.”

In 2024, the bureau ended fortnightly updates focused on La Nina and El Nino watches and alerts – including a dial with a pointer showing swings between the climate drivers – and instead stressed its short- and long-term forecasts provided a better guide.

“In a changing climate, it is more difficult to make predictions based on events when they are looked at individually – climate systems are complex and cannot be explained by just one influencing factor,” climate manager Karl Braganza said at the time.

The bureau continues to publish information on climate driver influences in the Pacific, Indian and southern oceans on a southern hemisphere monitoring phase.

Its April 14 report says all models, including the bureau’s, forecast the tropical Pacific to continue warming in coming months.

“There is variation across models in the rate at which El Nino thresholds may be reached, with some suggesting development as early as May, while others show a slower warming with thresholds not being met until July,” it says.

“Ocean-atmosphere coupling – where the ocean and atmosphere act to reinforce each other – is required for a sustained El Nino state.”

Most models also indicate a positive Indian Ocean Dipole – which contributes to drier eastern Australian weather – could develop over winter and spring, but forecast uncertainty is high and there’s a large spread of possible outcomes.

An Australian Research Council report has noted the severe droughts of 1982, 1994, 2002, 2006 and 2015 coincided with El Nino.

The bureau says some El Nino years have been followed by severe summer fires, including Ash Wednesday on February 16 1983 and the 2002-03 and 2006-07 seasons.

The spring bushfires in the Blue Mountains in October 2013 occurred during a neutral year, while Black Saturday on February 7 2009 followed a weak La Nina but a positive Indian Ocean Dipole.

The Black Summer bushfires of 2019-20 followed Australia’s driest year on record. The El Nino Southern Oscillation was neutral that year, and the bureau says a “very strong” positive Indian Ocean Dipole was one of the main climate influences.

It’s still early days to say what the peak spring and summer bushfire seasons in eastern and southern Australia will bring, but history suggests people in riskier areas will be hoping for more favourable forecasts in coming months.

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