Climate outlook for June to September

Climate outlook overview

• Winter (June to August) rainfall is very likely to be above median for much of Australia, but below median for south-western Australia, and western Tasmania.
• June to August maximum temperatures are likely to be above median for northern, south-western, and far south-eastern parts of Australia, but below median generally elsewhere.
• Minimum temperatures for June to August are very likely to be warmer than median across almost all of Australia.
• The chance of a negative Indian Ocean Dipole, the continuing La Niña, warmer than average waters around northern Australia, and other localised drivers are likely to be influencing this outlook.

Above median winter rainfall likely for most of Australia, but drier in south-west Australia and western Tasmania

• Winter (June to August) rainfall is likely to be above median for much of Australia (chance of exceeding the median is greater than 60%), with eastern and central regions very likely to exceed the median (chances are greater than 80%). However, much of the South West Land Division in WA and western Tasmania are likely to be below median (chances of exceeding the median are less than 40%).
• Large parts of eastern Australia are around 2 to 3 times more likely than normal to have unusually high (in the top 20% wettest of all past years) June to August rainfall.
• It should be noted that May to September is the northern Australia dry season. This means tropical northern Australia typically has very low rainfall totals during this time (large areas less than 25 mm for the season), and only a small amount of rainfall is needed to exceed the median.
• The June and July outlooks are broadly similar to the three-month outlook, although the chances of above median rainfall are less emphatic, with above median monthly rainfall generally likely away from the south-west of Australia, the south-east mainland coast, and Tasmania. Additionally, in July, the northern tropics have a neutral rainfall outlook.
• Past accuracy for June to August rainfall is moderate to high for most areas of Australia, with low accuracy for parts of the northern tropics and south-west SA.

Warmer winter days for north and far south, cooler days likely generally elsewhere

• Winter (June to August) maximum temperatures are likely to be above median for the northern tropics, south-west WA, far south-east SA, south-east NSW, southern and eastern Victoria, and Tasmania (generally greater than 70% chance). Below median maximum temperatures are likely for a broad area stretching from the Pilbara coast in WA, through most of SA and the southern NT, southern Queensland, most of New South Wales away from the south-east, and north-west Victoria (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 June to August over the northern tropics and Tasmania (1.5 to greater than 4.0 times the usual chance). There is an increased chance of unusually low maximum temperatures (in the bottom 20% of historical records) in a broad area stretching from the Pilbara coast of WA, through most of SA and the southern NT, across the southern half of Queensland, northern and western NSW and north-west Victoria (1.5 to 3.0 times the usual chance).
• Minimum temperatures for June to August are likely to be warmer than median for the majority of Australia (chances greater than 60%), with most areas very likely to be warmer (chances are greater than 80%). The chance is lower (generally less than 60%) for an area of central western WA.
• There is an increased chance of unusually high minimum temperatures (in the top 20% of historical records) for June to August across much of Australia (1.5 to greater than 4.0 times the usual chance), excluding most of the southern half of Western Australia. The highest chance of unusually warm minima is across the northern tropics.
• Past accuracy for June to August maximum temperatures is moderate to high for most areas of Australia, with low accuracy across the south-east Northern Territory, extending into parts of western Queensland. For minimum temperatures, accuracy is moderate to high across most of Australia, grading to low to very low accuracy across southern parts of the mainland, with low accuracy also across the Pilbara region in Western Australia.  

Climate influences

The winter climate outlook reflects several significant climate influences, including:

• La Niña remains active in the tropical Pacific. Most model outlooks indicate a return to neutral El Niño–Southern Oscillation (ENSO) conditions during winter. However, cooler than average sea-surface temperatures in the central tropical Pacific during June to August are likely to persist. Coupled with warmer ocean temperatures in the western tropical Pacific, this would favour average to above average winter rainfall for eastern Australia. Model accuracy at this time of year is moderate for ENSO.
• The Indian Ocean Dipole (IOD) is currently neutral. However, the IOD index has become more negative over the past fortnight. Outlooks indicate the potential for a negative IOD developing in the coming months. Model outlooks have low accuracy forecasting the IOD at this time of year and hence some caution should be taken with IOD outlooks beyond May. However, there is consistency across the IOD forecasts from all international models. While a neutral IOD has little influence on Australian climate, a negative IOD increases the chances of above average winter–spring rainfall for large parts of Australia. It also increases the chances of warmer days and nights for northern Australia.
• Above average sea-surface temperatures, particularly around northern Australia, are also likely to be contributing to the wetter outlooks and warmer nights forecast for many areas.
• The Southern Annular Mode (SAM) index is expected to be neutral for the next week then positive or close to positive for the following three weeks. During the winter months, a positive SAM typically has a drying influence for parts of south-west and south-east Australia.
• Australia's temperature and rainfall variability are also influenced by global warming caused by human activities. Australia's climate has warmed by around 1.47 °C for the 1910–2020 period. Southern Australia has seen a reduction of 10% to 20% in cool season (April–October) rainfall in recent decades. There has also 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.