Climate outlook for August to November

Long-range forecast overview

• For August to October, below median rainfall is likely (60% to 80% chance) for most of Australia, increasing to very likely (greater than 80% chance) for Victoria, south-east SA and south-west WA.
• For August to October, above median maximum temperatures are very likely (greater than 80% chance) for almost all of Australia.
• For August to October, minimum temperatures are likely to very likely (60% to greater than 80% chance) to be above median for almost all of Australia.
• This forecast is influenced by a number of factors, including likely El Niño development, the potential development of a positive Indian Ocean Dipole, and record warm oceans globally.

Drier than median August to October for most of Australia

• For August, below median rainfall is likely (60% to 80% chance) for much of eastern Australia, some northern areas of the NT and WA, and south-western WA. Percentage chances increase to very likely (greater than 80% chance) for parts of Victoria, south-east SA and far south-west WA.
• For August to October, below median rainfall is likely (60% to 80% chance) for most of Australia, increasing to very likely (greater than 80% chance) for large parts of Victoria, south-east SA and south-west WA.
• For August to October, large parts of eastern and south-western WA are at least twice as likely to receive unusually low rainfall (unusually low rainfall equates to the driest 20% of August to October periods from 1981 to 2018). The chance of unusually low rainfall increases to four times as likely for large areas of south-east SA, south-west Vic and far south WA.
• Past accuracy of August to October long-range forecasts for the chance of above median rainfall has generally been moderate to high for most of Australia, with low to very low accuracy for southern and central parts of WA and parts of south-west SA.

Warmer than median days and nights for almost all of Australia during August to October

• For August, above median maximum temperatures are likely to very likely (60% to greater than 80% chance) for most of Australia, with the exception of some inland areas of northern Australia where temperatures have an equal chance of above or below median.
• For August to October, above median maximum temperatures are very likely (greater than 80% chance) for almost all of Australia.
• For August to October, most of Australia is at least three times as likely to experience unusually high maximum temperatures (unusually high maximum temperatures equate to the warmest 20% of August to October periods from 1981 to 2018), with the chance of unusually high maximum temperatures increasing to more than four times as likely for areas of western and interior WA and north-eastern Tasmania.
• For August, above median minimum temperatures are likely to very likely (60% to greater than 80%) for much of eastern Australia and northern WA.
• For August to October, minimum temperatures are likely to very likely (60% to greater than 80% chance) to be above median for almost all of Australia.
• Past accuracy of the August to October chance of above median maximum temperature long-range forecasts has been high to very high across most of Australia. For minimum temperatures, accuracy has been moderate to high, excluding regions of low accuracy in northern WA and parts of south-eastern Australia.

Climate influences

The long-range forecast reflects known impacts from several significant climate drivers:

• The El Niño–Southern Oscillation (ENSO) outlook is at El Niño Alert. In the past, when we have reached El Niño Alert, events have subsequently developed around 70% of the time. The Bureau's climate model suggests El Niño development during winter. El Niño typically increases the chance of below average winter-spring rainfall for the eastern half of Australia, as well as above average daytime temperatures for the southern two-thirds of Australia.
• The Indian Ocean Dipole (IOD) is currently neutral. The Bureau's climate model suggests positive IOD development during winter. During winter–spring, a positive IOD typically supresses rainfall over much of Australia, and if it coincides with El Niño, it can exacerbate El Niño's drying effect.
• The Southern Annular Mode (SAM) index is currently negative and expected to remain negative for the next two weeks. A negative SAM typically increases rainfall for parts of south-west and south-east Australia during winter.
• Longer-term trends: Australia's climate has warmed by around 1.47 °C in the period from 1910 to 2021, leading to an increase in the 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. As a result, the model accounts 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.