Long-range forecast overview

The long-range forecast for December to February shows:

• above average rainfall is likely for most of Australia, particularly during December
• an increased chance of unusually high rainfall for parts of eastern and north-western Australia
• warmer than average days are likely across large parts of the country
• warmer than average nights are very likely across almost all of Australia with unusually high overnight temperatures for much of northern, eastern and western Australia.

Rainfall—Summary

Rainfall is likely to be above average for most of Australia

December to February

• Rainfall is likely (60 to 80% chance) to be above average for much of eastern Australia, including eastern Tasmania, and much of Queensland, NSW and Victoria; and large parts of SA, WA and the northern NT.
• There is an increased chance of unusually high rainfall¹ for parts of Queensland's coastal regions and the Cape York Peninsula, southern NSW, eastern parts of Victoria, Tasmania and SA, northern WA and parts of the interior.
• The highest chance of above average rainfall for the season is forecast for December, with almost all of Australia likely to experience above average December rainfall. The chances of above average rainfall for this month have increased in recent weeks.
• The chance of above average rainfall generally decreases as the summer progresses. January rainfall is likely to be within the typical range for the month across most of Australia.

¹Unusually high rainfall is defined as the highest 20% of December to February rainfall observations from 1981 to 2018.

Temperature—Summary

Unusually warm nights likely across most of Australia

December to February

• Above average maximum temperatures are likely to very likely (60% to greater than 80% chance) for large parts of Australia while above average minimum temperatures are very likely across almost all of Australia.
• Maximum temperatures are likely to be within the typical range for the season for large parts of central and eastern NSW, eastern parts of WA, south-west SA, the central NT, and southern Cape York Peninsula in Queensland.
• There is an increased chance of unusually high maximum temperatures² across Tasmania and western WA, and parts of south-eastern SA and western Victoria, with up to 3.5 times the normal chance.
• There is an increased chance of unusually high minimum temperatures² across Australia, particularly in the north and large areas in the east and west of the continent, where the likelihood is more than 4 times the normal chance.
• For December alone, maximum temperatures are likely to very likely (60% to greater than 80% chance) to be below average for eastern WA, most of the NT and parts of inland Queensland, and likely to very likely (60% to greater than 80% chance) to be above average for western WA and parts of south-east Australia; elsewhere maximum temperatures are likely to be in the typical range for the season.
• There is an increased chance of unusually low maximum temperature³ for the Pilbara and Kimberley districts in WA in December, up to 3.5 times the normal chance.

²Unusually high maximum and minimum temperatures are those in the warmest 20% of December to February days and nights, respectively, between 1981 and 2018.

³ Unusually low maximum temperatures are those in the coolest 20% of December day temperatures between 1981 and 2018.

We generate forecasts up to 4 months ahead using our long-range forecast model, ACCESS-S. The model simulates evolutions in the state of the atmosphere and oceans for the coming months. It uses millions of observations from satellites and instruments on land and at sea.

We monitor global and hemispheric climate indicators that can support our understanding of longer-term predictability. These indicators are mainly associated with interactions between the atmosphere and ocean.

For general information, our monitoring of these climate indicators shows:

• Global SSTs remain at near record levels as at 24 November, with temperatures since July falling just short of the record temperatures observed during 2023, yet above all other years since observations began in 1854. The sustained nature of this significant global ocean heat suggests that climate indicators such as ENSO and IOD may not behave or evolve as they have in the past.
• The Bureau's model suggests SSTs are likely to remain within the ENSO-neutral thresholds (−0.8 °C to +0.8 °C) throughout the forecast period to February 2025. Of the 6 other climate models surveyed, two models suggest SSTs in the tropical Pacific are likely to exceed the La Niña threshold (below −0.8 °C) throughout December to February, which is sufficient time to be classified as a La Niña event, though this would be considered a very short-lived event compared to the historical record. All models forecast neutral ENSO values by March.
• The Indian Ocean Dipole (IOD) index has been below the negative IOD threshold (−0.40 °C) since mid-October. If the IOD index remains below the threshold for another week, it would indicate a negative IOD event is underway. All but one of the surveyed climate models indicate that the IOD index is expected to return to neutral levels in December, in line with the typical IOD event lifecycle.
• The Southern Annular Mode (SAM) index is neutral as at 22 November, having been positive for most of November. It is forecast to become positive again in the coming fortnight. SAM is also forecast to have a greater than usual chance of being in the positive phase during December.