Climate outlook for October to January

Long-range forecast overview

• For October to December, below median rainfall is likely to very likely (60% to greater than 80% chance) for most of Australia, excluding the interior of WA and much of central Australia.
• For October to December, above median maximum temperatures are very likely (greater than 80% chance) for almost all of Australia.
• For October to December, above median minimum temperatures are very likely (greater than 80% chance) for almost all of Australia, excluding central parts of the Queensland coast.
• The long-range forecast is influenced by several factors, including likely El Niño and positive Indian Ocean Dipole development, and record warm oceans globally.

Drier than median October to December likely for most of Australia, excluding the interior of WA

• For October, below median rainfall is likely to very likely (60% to greater than 80% chance) for most of the eastern two-thirds of Australia and likely (60% to 80% chance) for southern WA.  
• For October to December, below median rainfall is likely (60% to 80% chance) for southern WA and most of the eastern two-thirds of Australia. Chances of below median rainfall increase to very likely (greater than 80% chance) for areas of southern Australia and eastern Queensland.
• Unusually low rainfall is at least twice as likely for parts of southern and eastern Australia. Unusually low rainfall equates to the driest 20% of October to December periods from 1981 to 2018.
• Past accuracy of October to December long-range forecasts for the chance of above median rainfall is moderate to high for most of Australia, decreasing to low to very low for some central and western areas of the mainland.

Warmer than median October to December days and nights for almost all of Australia

• For October, above median maximum temperatures are very likely (greater than 80% chance) across almost all of Australia, excluding Cape York Peninsula.
• For October to December, above median maximum temperatures are very likely (greater than 80% chance) for almost all of Australia.
• For October to December, most of Australia is at least 2.5 times likely to experience unusually high maximum temperatures (unusually high maximum temperatures equates to the warmest 20% of October to December periods from 1981 to 2018), with chances increasing to more than four times likely for most of western and central WA, and parts of eastern Australia.
• For October, above median minimum temperatures are likely to very likely (60% to greater than 80% chance) for most of the southern two-thirds of Australia, increasing to very likely (greater than 80% chance) for most of WA.
• For October to December, minimum temperatures are very likely (greater than 80% chance) for almost all of Australia, excluding central parts of the Queensland coast.
• For October to December, most of Australia, excluding parts of the south-east and north-east, is at least 2.5 times likely to experience unusually high minimum temperatures (unusually high minimum temperatures equates to the warmest 20% of October to December periods from 1981 to 2018), with chances increasing to more than four times likely for parts of western and eastern Australia.
• Past accuracy of the October to December long-range forecast has been high to very high across all of Australia for chance of above median maximum temperature and moderate to high for chance of above median minimum temperature.

Climate influences

The long-range forecast reflects known impacts from several significant climate drivers:

• The El Niño–Southern Oscillation (ENSO) outlook remains at El Niño Alert. In the past, when we have reached El Niño Alert, events have subsequently developed around 70% of the time. El Niño typically increases the chance of below average spring rainfall for the eastern half of Australia, and above average daytime temperatures for the southern two-thirds of Australia.
• Climate models suggest a positive Indian Ocean Dipole (IOD) is likely in spring. The last three weeks have seen the Indian Ocean Dipole (IOD) index exceed the positive IOD threshold of +0.40 °C. However, several more weeks of positive IOD values above the threshold are needed for greater confidence that a positive IOD event is underway. A positive IOD typically decreases spring rainfall for much of Australia.
• The Southern Annular Mode (SAM) index is currently neutral and is expected to become slightly negative and then return to neutral later in September.
• Longer-term trends: Australia's climate has warmed by around 1.47 °C in the period from 1910 to 2021, leading to an increased frequency of extreme heat events. Southern Australia has seen a 10 to 20% reduction in cool season (April to October) rainfall in recent decades.

The Bureau's climate model simulates the physics of atmospheric, oceanic, ice, and land surface processes and uses millions of observations from satellites as well as in-situ instrumentation on land and at sea. These simulations enable the model to account for the influence of climate change and natural climate drivers like ENSO, IOD, the Madden–Julian Oscillation (MJO) and SAM in its long-range forecasts.