El Niño's Impact on Australian Weather and Climate Explained

Are we likely to see more TCs during summer with this climate swing?

— Nick

Hi Nick, looping in Climate Council's Andrew Watkins to answer this one for you:

Another great question.

We usually expect there to be fewer cyclones during an El Niño year as the waters to our north are not quite as warm as in La Nina years.

Climate change is also reducing the frequency of cyclones. However, if we do get any cyclones, they could be stronger. That's because a warmer atmosphere can carry more moisture, and it's the energy carried by the evaporation process that fuels our tropical cyclones.

ABC News Breakfast meteorologist Nate Byrne is now taking us back in time to the last El Niño event we saw in Australia:

I reckon some people think back to the 2019/2020 Black Summer, but that wasn't an El Niño (it happened after an event in 2015-2016, followed by years of drought).

The latest El Niño was in 2023-2024. It started in mid-2023 and developed as a moderate to strong El Niño that set the record for Australia's driest 3 months (from August to October), but then it weakened and the summer brought the east a bunch of rain events, bringing devastating floods even as El Niño carried on.

It dissipated in April 2024. Because of the quick swing, we didn't see a lot of the long-term impacts of an El Niño, so many people in Australia didn't really even notice. That wasn't the case across the board, and certainly not the case overseas.

Will it be much hotter this summer across the country?

— Richard S

Hi Richard, thanks for your question.

Here's what ABC News Breakfast meteorologist Nate Byrne has to say:

It's certainly possible, but that hasn't always happened in El Niño years beyond what we normally get.

The likelihood of heat in the south is increased, and we do tend to get more heatwaves. Interestingly, it's partly because we generally see fewer cyclones, which can knock a lot of heat out of the tropics (and often deliver much-needed summer rain).

That's not to say we won't see cyclones, though — Australia has never recorded a year without a cyclone crossing the coast.

The increased heat and heatwave risk can also worsen our bushfire outlook, but that also depends a lot on other factors including our cool season preparation and hazard reduction.

How do the El Nino influences on Australia's weather and climate play out on the east coast v west coast?

— Clint

Morning Clint,

I've lined up ABC News Breakfast meteorologist Nate Byrne to take this question. Here's what he says:

It varies wildly across the country, and at different times (and depending on other climate drivers that happen to our west and south) because we are so vast and have such diverse weather patterns.

Eastern Australia tends to bear the brunt, with reduced winter rainfall, warmer temperatures and more frost. That extends through the south to Western Australia, but the effect is generally weaker the further west you go. Also, we generally get less snow over the Alps in the southeast (but that doesn't mean there won't be some good dumps!).

The warmer temperatures and lower rainfall persist into spring for eastern Australia as a whole, though the eastern seaboard gets fairly average falls, while WA tends to depend more on what's going on in the Indian Ocean. Then we start to feel it in the tropics, with the build-up holding on for longer in the Top End. The later onset of the wet season can choke off a supply of summer rain for the rest of the continent, but that all depends on exactly when and where tropical systems form, and how they move and develop (and they don't need to get to cyclone strength to still be a major event).

Otherwise, El Niño tends to make our summers swing more wildly — think an increased risk of bushfires and heatwaves — but more heat in the atmosphere can also lead to big rain events and flooding. We'll have a much better idea towards the end of spring.

If it carries on into autumn, we start swinging back to the things we feel in winter — reduced rainfall, warmer temperatures and more frost for the eastern and southern states.

Keep in mind that this is a global event — typically global temperatures rise following an El Niño event, and that can contribute to even more extreme weather events in the long term.

How is this going to affect our weather moving forward?

— Ashleigh

Day to day, we'll barely notice it.

El Niño is a nudge on the weather, but one that adds up over time. Temperatures will be slightly warmer over winter ON AVERAGE — we'll still get cold days and nights, but generally not quite as cold as they'd normally be.

Similarly, there will be slightly less rain than normal ON AVERAGE — don't put away your umbrella or gumboots but maybe think twice before having that super-long shower. Also, it might not make sense at first blush, but the reduced rainfall usually means clearer skies which — despite the slightly elevated temperatures — can mean more frosty mornings.

Typically, El Niño lasts through winter and spring and starts to decay in summer, but they can last up to a year, and occasionally we can get subsequent back-to-back El Niño events for 2 years or more. That's where things get really dangerous for Australia — multiple winters of low rainfall and warmer temperatures can significantly elevate the summer bushfire and drought risk.

It can also reduce activity in the tropics later in the year (we typically end up with fewer cyclones than the average), and it can delay the onset of the northern wet season.

The tricky thing is that no two El Niño events are the same — the weather is still the unknown variable with this climate push, and it just takes one wayward cyclone, deep cold front, or east coast low to change our fortunes significantly. To complicate things even further, there are other climate drivers — the Indian Ocean Dipole (IOD) and the Southern Annular Mode (SAM) that can sway the pendulum and either reinforce or combat El Niño.

Finally, how we prepare and how we behave can change things too — good fuel reduction and land management policies, water conservation and disaster preparedness can take the sting out of the tail, buy us time, or at least help us recover more quickly when things get tough.

How will this affect the bushfire season in Victoria?

— Connor

Will the El Niño result in bushfires as bad as the Black Saturday Bushfires?

— James

Hi Connor and James,

It looks like you're both on the same page when it comes to bushfires.

I've got Climate Council's Andrew Watkins here to answer that one:

Southern Australia is one of the most fire prone places on the planet. But unfortunately we need to be even more vigilant in our bushfire season because climate change has lengthened these fire seasons and made it possible for dangerous fires to burn at any time.

We don't need El Niño to have bad bushfires, for example 2019 when the Black Summer fires started was not an El Niño year. This past summer when fires destroyed more than 400 houses in Victoria, we were actually under a La Nina event which is supposed to bring cooler and wetter conditions.

But El Nino does typically provide a warmer and drier spring in the lead into the summer, which can often mean a greater fire risk, especially in Queensland and NSW, and can raise the risk of severe fire weather over the summer.

Fires can be difficult to predict but we should get a better look at the coming fire seasons at the end of winter.