Climate outlook for May to August

Long-range forecast overview

• For May to July, below median rainfall is likely to very likely (60% to greater than 80% chance) for most of Australia.
• May to July maximum temperatures are likely to very likely (60% to greater than 80% chance) to be warmer than median for most of Australia.
• Above median May to July minimum temperatures are likely to very likely (60% to greater than 80% chance) for most of the country excluding inland northwest, central and eastern regions.
• This forecast is being influenced by several factors including an ENSO-neutral pattern (neither El Niño nor La Niña) tending towards El Niño in the latter part of the forecast period, and the chance that a positive IOD event may develop in the coming months, as well as longer-term trends.

Drier than average May to July for almost all of Australia

• For May, below median rainfall is likely to very likely (60% to greater than 80% chance) for most of Australia, excluding western Tasmania, southern Victoria, much of northern WA and Cape York coastal regions.
• For May to July, below median rainfall is likely (60 to 80% chance) for most of Australia, with the northeastern Top End of the NT, southeastern SA, south-east Queensland and south-western WA very likely (greater than 80% chance) to be below median.
• For May to July, broad parts of the country are at least twice as likely to receive unusually low rainfall (amongst the driest 20% of records at this time of the year), including southern parts of the continent including broad areas of the south-west and south-eastern parts of the country.
• It should be noted that May marks the beginning of the northern Australian dry season. This means tropical northern Australia typically has very low rainfall totals, and only a small amount of rainfall is needed to exceed the median.
• Past accuracy of May to July long-range forecasts for chance of above median rainfall has generally been high for to very high for most of Australia. Accuracy is low for parts of the Gulf Country in QLD and northern parts of WA and NT.

Warmer than average days for most of Australia during May to July

• For May, above median maximum temperatures are likely to very likely (60% to greater than 80% chance) for southern WA, most of the Top End of the NT and eastern QLD. Below median maximum temperatures are likely (60 to 80% chance) for areas of Victoria, south-east NSW and a strip extending from northern WA across to western Queensland.
• May to July above median maximum temperatures are very likely (greater than 80% chance) for much of Australia, decreasing to likely (60 to 80% chance) for inland northern and central Australia, excepting central NT and the Gulf country where the chances of above or below median temperatures .
• The southern two-thirds of Australia is at least 1.5 times as likely to experience unusually high maximum temperatures during May to July (amongst the warmest 20% of records at this time of the year), with the South-west Land Division in WA being more than three times as likely.
• For May, above median minimum temperatures are likely (60 to 80% chance) for most of Tasmania and Victoria, parts of southeast SA and western parts of the Pilbara and Gascoyne in WA, increasing to very likely (greater than 80% chance) for the Cape York Peninsula in QLD. Below median minimum temperatures are likely for central inland regions of the country extending to include most of QLD and NSW, as well as most of the Kimberley.
• For May to July, minimum temperatures are likely to very likely (60 to greater than 80% chance) to be above median for Victoria, Tasmania, southern SA, most of WA, northern NT and Cape York Peninsula.
• Past accuracy of the May to July chance of above median maximum temperature long-range forecasts has been high to very high across virtually all of Australia. For minimum temperatures, accuracy has been moderate to very high for most of Australia, tending to low skill for southern parts of the mainland.

Climate influences

Long-range forecasts reflect several significant climate influences. These include:

• Long-range forecasts currently suggest El Niño development during winter. The Bureau's model is indicating a slightly earlier transition than the other models, with El Niño thresholds potentially being reached during May. Long-range forecasts for La Niña/El Niño increase in accuracy as winter approaches. El Niño increases the chances of below average rainfall for eastern Australia.
• The Indian Ocean Dipole (IOD) is currently neutral. Long-range forecasts suggest a positive IOD event may develop by June. However, long-range forecasts for the IOD made during this time of the year have historically had low accuracy. A positive IOD increases the chances of below average rainfall for much of south-eastern and central Australia.
• The Southern Annular Mode (SAM) index is currently neutral and expected to become slightly positive in the coming days before returning to neutral values. At this time of the year, SAM has little influence on Australian rainfall patterns. As we head into winter, positive SAM typically reduces rainfall across south-western and south-eastern parts of the country.
• Sea surface temperatures are warmer than average in the Coral Sea and across the southern Tasman Sea. A cool anomaly has formed over the coasts of NSW and northern WA.
• Longer-term trends: Australia's climate has warmed by around 1.47 °C in the period 1910–2021, leading to an increase in the frequency of extreme heat events. Southern Australia has seen a reduction of 10 to 20% in cool season (April–October) rainfall in recent decades.
• Since the 1990s, in the absence of strong 'wet' drivers, autumn rainfall in southern Australia has generally been below average.

• 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 long-range forecasts.