Climate outlook for October to January

Long-range forecast overview

• October to December rainfall is likely to be below median for much of Australia away from inland northern areas.
• October to December maximum temperatures are very likely to be above median across Australia.
• October to December minimum temperatures are very likely to be above median almost nationwide.
• 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 much of Australia

• For October, below median rainfall is likely (60 to 80% chance) for most of Australia, apart from north-western and central WA, and small parts of coastal NSW. Parts of the northern NT and south-eastern mainland are very likely to be below median (greater than 80% chance).
• October to December rainfall is likely (60 to 80% chance) to be below median for much of Australia. However, chances of above or below median rainfall is roughly equal for parts of inland northern and central WA, southern and central NT, and much of western Queensland.
• Unusually low rainfall is at least twice as likely for parts of south-west WA, Queensland's central coast, south-east SA, southern and north-eastern Victoria, and western Tasmania. 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 south-western and interior WA, south-western NT and north-western SA.

Warmer than median October to December days and nights for almost all of 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, most of Australia is at least 3 times likely to experience unusually high maximum temperatures, with chances increasing to more than 4 times likely for most of western and central WA, and parts of central and south-eastern Australia. Unusually high maximum temperatures equate to the warmest 20% of October to December periods from 1981 to 2018.
• For October to December, minimum temperatures are very likely (greater than 80% chance) for almost all of Australia apart from a small area of Queensland's North Tropical Coast.
• For October to December, broad areas of Australia are at least 2.5 times likely to experience unusually high minimum temperatures, with chances increasing to more than four times likely for parts of central WA, southern Queensland, and north-east NSW. Unusually high minimum temperatures equate to the warmest 20% of October to December periods from 1981 to 2018.
• Past accuracy of the October to December long-range forecast for chance of above median maximum temperatures has been high to very high across all of Australia. For minimum temperatures, accuracy is high to very high for most of Australia, dropping to low to moderate for parts of north-western Australia.

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, with El Niño development likely during spring. 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.
• A positive Indian Ocean Dipole (IOD) is very likely in spring. The last four weeks have seen the Indian Ocean Dipole (IOD) index exceed the positive IOD threshold of +0.40 °C. If the IOD index continues to remain above this threshold, a positive IOD event will be considered underway. A positive IOD typically decreases spring rainfall for much of Australia.
• The Southern Annular Mode (SAM) index is currently negative and is expected to remain negative over the coming week, returning to neutral in late September. During spring, a negative SAM is associated with decreased rainfall across parts of eastern parts of both NSW Victoria and increased rainfall over western Tasmania.
• 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.