Climate outlook for December to March
Climate outlook overview
- December to February rainfall is likely to be above median for much of the eastern states of Australia, with highest chances for eastern Queensland, eastern NSW and eastern Victoria.
- December to February maximum temperatures are likely to be above median for most of Australia, with below median daytime temperatures likely for eastern NSW, south-east Queensland and far eastern Victoria.
- There is an increased chance of unusually high maximum temperatures (in the top 20% of historical records) for December to February for much of Australia away from the east (1.5 to 3.0 times the usual chance).
- There is an increased chance of unusually high rainfall (in the top 20% of historical records) for December to February over most of the eastern states, as well as small patches of SA, the NT and northern WA (1.5 to 3.0 times the usual chance).
- Minimum temperatures for December to February are very likely to be warmer than median for most of Australia, with south-eastern WA and western SA having roughly equal chances of warmer or cooler than median nights.
- The La Niña in the Pacific Ocean and the positive Southern Annular Mode (SAM) state are likely influencing the above median rainfall outlooks.
Wetter summer likely for eastern states, mixed outlook elsewhere
- December to February rainfall is likely to be above median for NSW, the eastern two-thirds of Queensland and Victoria, eastern Tasmania and patches of eastern SA, NT and northern WA (chance of exceeding median is greater than 60%). Chances are highest for NSW, eastern Queensland and eastern Victoria, where chances of above median summer rainfall are 70-80% in large patches. Central WA and western Tasmania are likely to have below median rainfall (chance of exceeding the median is below 40%). The rest of Australia has roughly equal chances of above or below median rainfall (chance of exceeding the median is close to 50%).
- December rainfall is likely to be above median for Victoria, NSW, eastern Tasmania, and southern and eastern Queensland, as well as along the SA/NSW border. Conversely, large parts of northern and central WA, small patches of the central NT, small patches of northern SA and western Tasmania are likely to have below median rainfall. The rest of Australia has roughly equal chances of above or below median rainfall.
- There is an increased chance of unusually high rainfall (in the top 20% of historical records) for December to February over most of Victoria, NSW, eastern Queensland and eastern Tasmania, as well as small patches of SA, the NT and WA (1.5 to 3.0 times the usual chance). In any given outlook period, the chance of unusually high or low rainfall is around 20%. This means that a 40% chance of unusually warm conditions is twice the normal likelihood, while 60% is three times.
- The week of 6 to 12 December is likely to be wetter than median for most of Australia with the highest chances occurring over western NSW, eastern SA and western WA.
- Past accuracy for December to February rainfall is moderate to high for most of Australia, shifting to low accuracy along the WA border, the southern NT, southern parts of SA, along the Queensland-NSW border, and parts of Tasmania.
Colder days for NSW and south-east Queensland, warmer nights expected across Australia
- December to February maximum temperatures are likely to be above median for much of WA, the NT, SA, Tasmania, Victoria, western Queensland and the coastline of Queensland (greater than 60% chance). Below median daytime temperatures are likely for eastern NSW extending into far eastern Victoria and south-east Queensland (chance of exceeding the median is less than 40%).
- There is an increased chance of unusually high maximum temperatures (in the top 20% of historical records) for December to February over most of WA, the NT, SA, western Victoria and Tasmania (1.5 to 4.0 times the usual chance). In any given outlook period, the chance of unusually high or low maximum temperatures is around 20%. This means that a 40% chance of unusually warm conditions is twice the normal likelihood, while 60% is three times. There is an increased chance of unusually low maximum temperatures for parts of eastern NSW (1.5 to 2.5 times the usual chance).
- Minimum temperatures for December to February are likely to be warmer than median for most of Australia (chances are greater than 60%), with most areas very likely (greater than 80% chance). However, south-eastern WA, western SA and a small area of inland north-east NSW have roughly equal chances of above or below median overnight temperatures (chance of exceeding the median is close to 50%).
- There is an increased chance of unusually high minimum temperatures (in the top 20% of historical records) for December to February over most of Australia except south-east WA, north-east NSW away from the coast, and south-east Queensland away from the coast (1.5 to more 4.0 times the usual chance), with the highest likelihoods for northern Australia, Tasmania and central Victoria.
- Past accuracy for December to February maximum temperatures is high to very high for almost all of Australia, with moderate to low accuracy for the southern NT. For minimum temperatures, accuracy is high to very high across the southern half of the country and parts of the far north, with moderate to low accuracy for far northern WA, extending into central parts of the NT and across through central parts of Queensland.
Climate influences
- La Niña has become established in the tropical Pacific. Climate models indicate La Niña thresholds are likely to be maintained until late summer. This pattern is likely to be contributing to the wetter than median outlooks for eastern Australia.
- The negative Indian Ocean Dipole (IOD) is approaching its end, as forecast by models and in line with its typical seasonal cycle. A neutral IOD has little influence on Australian climate.
- The Southern Annular Mode (SAM) has generally been positive for several weeks. It is expected to remain at positive levels until the end of the year. A positive SAM at this time of year typically brings above average rainfall to parts of eastern Australia, but below average rainfall for western Tasmania.
- The Madden-Julian Oscillation (MJO) has strengthened over the Maritime Continent and is expected to track eastwards into the western Pacific in the coming week. This scenario may assist the development of the monsoonal flow in the southern hemisphere.
- Sea surface temperatures (SSTs) are currently warmer than average around tropical Australia and are forecast to remain above average. These are likely contributing to the wetter and warmer outlooks for the coming months.
- Australia's temperature and rainfall variability are also influenced by global warming caused by human activities. Australia's climate has warmed by around 1.44 °C for the 1910–2019 period. Rainfall across northern Australia during its wet season (October–April) has increased since the late 1990s. In recent decades there has been a trend towards a greater proportion of rainfall from high intensity short duration rainfall events, especially 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.
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