Climate outlook for October to January

Climate outlook overview

• October to December rainfall is likely to be above median for the eastern half of Australia, but below median for parts of Western Australia and part of western Tasmania.
• Rainfall for the fortnight 12 to 25 September is likely to be above median for the eastern mainland states, around median for Tasmania and below median for the Kimberley in Western Australia.
• October to December maximum temperatures are likely to be above median across the north-western quadrant of Australia, most of the northern and western coasts, and across Tasmania; cooler than median days are likely across much of New South Wales and the southern half of Queensland.
• Minimum temperatures generally likely to be warmer than median for October to December over much of Australia, although there is roughly equal likelihood of warmer or cooler nights along the New South Wales central coast northwards to south-eastern Queensland, and in south-eastern Western Australia.
• All of the current negative Indian Ocean Dipole event, an increasing chance of La Niña emerging during spring, a positive Southern Annular Mode index, and warmer than average waters around northern Australia are likely to be influencing this outlook.

Wetter than average October to December likely for eastern half of Australia

• There is a moderate to high chance (greater than 70%) of above median rainfall for the fortnight 12 to 25 September for much of mainland Australia, and very high chance (greater than 80%) for much of Queensland, parts of New South Wales on the western side of the Great Dividing Range, and the western Top End; there is a moderate to high chance (greater than 70%) of below median rainfall for much of the Kimberley coast in Western Australia.
• During that fortnight, large parts of the Northern Territory, Queensland, and parts of New South Wales west of the Great Dividing Range have at least twice the average chance of unusually high rainfall (in the wettest 20% of all 12 to 25 September periods during 1981 to 2018).
• There is a moderate to high chance (greater than 70%) of above median October to December rainfall for much of the Top End and north-east of the Northern Territory, much of the eastern mainland states, and eastern Tasmania; below median rainfall is moderately likely (60% to 70% chance) for parts of Western Australia and the central west coast of Tasmania.
• The pattern is generally consistent throughout each of the three months in the outlook period, but November has the highest chance of above median rainfall across eastern Australia and the Top End.
• Large parts of the Top End, around the Gulf of Carpentaria, and northern to central Queensland have more than twice the average chance of unusually high October to December rainfall (in the wettest 20% of all such periods over 1981–2018), similar likelihood is also seen over eastern Tasmania, the eastern two thirds of Victoria, and south-eastern to central parts of New South Wales.
• Past accuracy for October to December chance of above median rainfall outlooks is moderate to very high for most of Australia with the exceptions of parts of Western Australia, most notably in the inland south-west and parts of the interior, where it is generally moderate to low.

Warmer days likely for the north-west, north and west coast, and Tasmania during October to December, but cooler for parts of the east

• For the fortnight 12 to 25 September, maximum temperatures are likely to very likely to be above median for most of the northern tropics (greater than 75% chance), but below median (greater than 70% chance) for most of the remainder of Australia.
• For the fortnight 12 to 25 September, minimum temperatures are likely to very likely to be above median for most of the northern tropics and for the Central West to western Pilbara districts of Western Australia (greater than 75% chance), but below median (greater than 70% chance) for much of the remainder of mainland Australia.
• For that fortnight, there is more than double the average chance of unusually high maximum and minimum temperatures (in the warmest 20% of all 12 to 25 September periods during 1981 to 2018) across the far northern tropics; however, there is a least two times the average chance of unusually cool maximum temperatures (in the coolest 20%) across much of Australia south of the tropics.
• October to December maximum temperatures are likely to be above median (greater than 65% chance) around the northern and western coasts, across the northern half of Western Australia and the west of the Northern Territory, and across Tasmania; cooler than median days are likely (greater than 65% chance) across much of New South Wales and the southern half of Queensland.
• Minimum temperatures are generally likely to be warmer than median for October to December over much of Australia, although there is roughly equal likelihood of warmer or cooler nights in the south-east of Western Australia, far western South Australia, and along the New South Wales central coast northwards to south-eastern Queensland.
• For October to December, there is more than double the average chance of unusually high maximum temperatures (in the warmest 20% of all October to December periods over 1981–2018) across the Kimberley and much of Tasmania away from the east coast.
• Unusually cool maximum temperatures (in the coolest 20% of all October to December periods over 1981–2018) are at least two times more likely than average across much of the eastern half of New South Wales and the south-eastern quarter of Queensland.
• There is four times the average chance of unusually high minimum temperatures (in the warmest 20% of all October to December periods over 1981–2018) for much of the northern tropics, and at least double the average chance for much of northern Australia, and south-eastern Australia except the eastern half of New South Wales.
• Past accuracy for October to December chance of above median maximum temperature outlooks is high to very high across all of Australia. For minimum temperatures, accuracy is high to very high for most of Australia.

Climate influences

The climate outlook reflects several significant climate influences. These include:

• At least a 70% chance of La Niña reforming later in 2022, with the ENSO Outlook currently at La Niña ALERT. Four of the seven models are suggesting La Niña thresholds are likely to be met by early to mid-spring.
• A negative Indian Ocean Dipole (IOD) event, which is currently under way. Outlooks indicate the negative IOD is likely to persist until at least the end of spring. A persistent negative IOD phase increases the chance of above average spring rainfall for much of Australia. It also increases the chances of warmer days and nights for northern Australia.
• The Southern Annular Mode (SAM) index, which is expected to remain mostly positive throughout spring. Positive SAM has a drying influence in western Tasmania at this time of year, but increases the likelihood of rainfall for parts of south-eastern Australia.
• Sea surface temperatures, which are currently warmer than average over the Maritime Continent and around much of Australia. This pattern is likely to be contributing to the wetter outlooks.
• Australia's temperature and rainfall variability are also influenced by global warming caused anthropogenic influences (human activities). Australia's climate has warmed by around 1.47 °C in the period between 1910 and 2020, leading to increased frequency of extreme heat events, reduction in cool season (April–October) rainfall in southern Australia (10 to 20%) in recent decades, and increased proportion of rainfall from high intensity, short duration rainfall events, particularly across northern Australia.

The Bureau's climate model uses the physics of our atmosphere, oceans, ice, and land surface combined with millions of observations from satellites and on land and sea. As a result, it incorporates the influence of climate change and natural climate drivers like ENSO, IOD, the MJO, and SAM in its outlooks.