Climate outlook for September to December

Long-range forecast overview

The long-range forecast for September to November shows:

• Above average rainfall is likely across much of eastern Australia.
• Daytime temperatures are likely to be above average in northern and south-eastern regions, with an increased chance of unusually warm days in the far north and south-east.
• Overnight temperatures are very likely to be above average across most of Australia, with an increased likelihood of unusually warm nights in northern, eastern, and central areas.

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Rainfall—Summary

Above average rainfall likely for much of eastern Australia

September to November

• Rainfall is likely to be above average (60% to over 80% chance) for most of the eastern half of Australia, with October showing the broadest signal across the region.
• Much of eastern and parts of central Australia face an increased chance of unusually high rainfall¹.
• From September to November, northern Australia transitions from the dry to the wet season, bringing increased humidity, storms, and showers.
• Rainfall is likely to be below average (60% to 80% chance) for parts of central Western Australia.
• Compared to last week, this week’s forecast shows a slight weakening of the wet forecast signal in inland areas of eastern Australia.

¹Unusually high rainfall is in the highest 20% of September to November rainfall, between 1981 and 2018.

Temperature—Summary

Warmer than average days likely in the north and south-east; warmer nights likely across most of Australia

September to November

• Maximum temperatures are likely to be above average (60% to over 80% chance) across most of northern and south-eastern Australia.
• Maximum temperatures are likely to be below average (60 to 80% chance) in parts of northern New South Wales.
• Maximum temperatures in other regions have an equal likelihood of being above or below the average, indicating a weak forecast signal.
• There is an increased chance of unusually high maximum temperatures² in far northern Australia, southern Victoria, and Tasmania.
• Minimum temperatures are likely to be above average (60% to over 80% chance) across most of Australia, except for parts of southern Western Australia.
• There is an increased chance of unusually high minimum temperatures² across most of the country, with strongest chances across the tropical north, Victoria and Tasmania.

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

We use our long-range model, ACCESS-S, to forecast up to four months ahead. It simulates how the atmosphere and oceans may change, using millions of observations from satellites, land stations, and ocean instruments.

We also track global climate indicators to help understand long-term weather patterns. These mainly reflect how the ocean and atmosphere interact.

Current climate indicators:

• Sea surface temperatures (SSTs) in the Australian region during July 2025 were +0.56 °C above average—the warmest July since 1900. SSTs have been at record or near-record levels since July 2024. Globally, July 2025 was the third warmest on record.

• SSTs for the week ending 31 August 2025 were warmer than average across much of the Australian region.

• Forecasts for September to November show warmer-than-average SSTs to the north, east, and south-east, with near-average temperatures around Western Australia and South Australia. Warmer oceans can provide increased moisture and energy, that can enhance the severity of storms and rain systems.
• The El Niño–Southern Oscillation (ENSO) is expected to remain neutral until at least January, though some models suggest borderline La Niña conditions in spring.
• Recent values and model forecasts suggest we are in the early stages of a negative Indian Ocean Dipole (IOD) phase, with further development likely in spring. Forecasts indicate a return to neutral in early summer.