There are early signs that El Niño and a positive Indian Ocean Dipole (IOD) could team up to cause abnormally dry and warm weather in Australia later this year. However, the ‘autumn predictability barrier’ is blurring the outlook for now.

La Niña on the way out

The Pacific Ocean is currently in a La Niña state, which began in spring last year (based on Bureau of Meteorology thresholds) and peaked in strength in January this year. This La Niña is now weakening and is expected to decay further in the coming weeks, with the Pacific Ocean most likely returning to a neutral state in autumn.

El Niño emerging

The transition to a neutral El Niño-Southern Oscillation (ENSO) state in the Pacific Ocean this autumn opens the door for a potential switch to El Niño later this year. While this is not guaranteed, it is not uncommon for El Niño to follow La Niña after the tropical Pacific Ocean passes through a neutral phase in the middle of the year.

Computer forecast guidance, including Australia’s ACCESS-S model and numerous highly regarded international models, predict that El Niño may develop in the second half of this year. The likelihood of El Niño emerging in the second half of 2026 ranges from above 90% from the Bureau's model to around 50 to 60% from other international models.

Autumn predictability barrier

One important thing to note about the current El Niño forecasts is that predictions made at this time of year are less reliable than forecasts initiated after the Southern Hemisphere’s autumn. This period of reduced certainty is known as the ‘autumn predictability barrier’, and it means that forecasters should have a clearer idea about the likelihood of El Niño as we get closer to winter in the Southern Hemisphere.

Hints at positive IOD

Another factor that may influence rainfall and temperatures over Australia later this year is the IOD. Extended forecasts suggest that the IOD could enter a positive phase from the middle of this year, although like the El Niño forecast, there is a high amount of uncertainty regarding this IOD outlook.

A positive IOD in the Indian Ocean is similar to El Niño in the Pacific Ocean in that they both promote abnormally warm and dry weather over Australia.

Warmer and drier outlook emerging

While it’s too early to know whether El Niño or a positive IOD will develop later this year, there are early signs that these two climate drivers could tip the scales towards warmer and drier weather during the second half of 2026.

Monthly temperature and precipitation forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) are responding to this, hinting at abnormally warm and dry conditions over Australia during the upcoming winter.

Image: Chance of wetter-than-normal conditions over Australia during June 2026. Source: Weatherzone / ECMWF SEAS5.

Image: Chance of warmer-than-normal monthly average daytime temperatures over Australia during June 2026. Source: Weatherzone / ECMWF SEAS5.

Weatherzone meteorologists will continue to monitor the Pacific and Indian Ocean over the coming months and provide updates on El Niño and the IOD via the Weatherzone news feed.