Climate outlook for June to September
Climate outlook overview
- Winter (June to August) is likely to be wetter than average across most of Australia.
- However, chances of a wetter than average winter are lower across southwest WA, the NSW and Victorian coasts, and Tasmania, where there are roughly equal chances of being wetter or drier than average. Across northern Australia it is the dry season, and typically have only low rainfall totals.
- Despite the wet winter outlook for many areas, the first week of June is likely to be drier and cooler than average for much of Australia, but warmer for southwest WA.
- Winter days are likely to be warmer than average across northern and eastern Australia as well as Tasmania, with parts of the southern mainland likely to see cooler days. Winter nights are very likely to be warmer than average nationwide.
- A warmer than average eastern Indian Ocean is currently the main influence on Australia's climate, increasing the moisture available to weather systems as they sweep across the country. To Australia's east, the tropical central and eastern Pacific Ocean is likely to cool over the winter months, which may indicate the early stages of a La Niña-like pattern.
Wetter winter likely for most of Australia
- Winter (June to August) is likely to be wetter than average for most of Australia (mostly 60–80% chance). However, the likelihood of a wetter or drier winter is roughly equal across much of northern Australia, southwest WA, the NSW and Victorian coasts, and Tasmania.
- Similarly, July to September is also likely to be wetter than average for most of the southern two-thirds of the continent (60–75% chance). However, the far southwest and southeast have slightly lower chances.
- While winter overall is likely to be wetter, the week of 1 June to 7 June shows most of the eastern two-thirds of the country, and northern and southern WA are likely to be drier than average (mostly 60-80% chance). Conversely, the Pilbara in WA is likely to have a wetter than average week.
- May marked the official start 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.
Warmer winter days for tropical north and east; cooler for southern mainland
- Cooler days are likely for the first week June for much of Australia, but southwest WA is likely to be warmer.
- Winter (June to August) days are likely to be warmer than average in tropical northern Australia, along the east coast and extending into Tasmania (greater than 80% chance for the tropical north, mostly 60–80% in other parts). However, southeast WA, southern SA, southwestern NSW and western Victoria are more likely to have cooler winter days (60–75% chance).
- Winter night-time temperatures are very likely to be warmer than average for most of Australia (65–80% chance for southwest and southeast Australia, greater than 80% chance elsewhere). The coastlines of southwest WA, southeast SA, western Victoria and northern Tasmania have roughly equal chances of warmer or cooler than average nights.
- A warmer than average eastern Indian Ocean is increasing the likelihood of northwest cloudbands interacting with rain-bearing fronts and troughs as they sweep across the country.
- The Indian Ocean Dipole (IOD) is currently neutral. While the Bureau's model has recently slightly eased in its chances for a negative IOD forming during winter, most other international models surveyed by the Bureau suggest a negative IOD remains more likely than not. Regardless, the eastern Indian Ocean is likely to remain warmer than usual, maintaining the wetter than average winter outlook for Australia. Caution should be exercised with using IOD forecasts issued during autumn, as they are less accurate than forecasts made at other times of the year.
- Negative IOD events typically increase the likelihood of above average winter-spring rainfall across southern Australia. They also increase the likelihood of cooler days in the south, and warmer days in the north.
- The El Niño–Southern Oscillation (ENSO) is likely to remain neutral over winter, though cooling towards La Niña levels is possible by the end of winter.
- The Southern Annular Mode (SAM) is forecast to be positive for the next two to three weeks. During winter, a positive SAM typically means less rainfall for southwest WA, southern Victoria and Tasmania.
- Australia's temperature and rainfall variability are also influenced by global warming caused by human activities. Australia's climate has warmed by around 1.4 °C since 1910, while southern Australia has seen a reduction of 10–20% in cool season (April–October) rainfall in recent decades.
- The Bureau's climate model uses the physics of our oceans, ice and land surface combined with millions of observations from satellites and on land and sea. As a result, it includes the influence of climate change and natural climate drivers like ENSO, IOD, the MJO and SAM in its outlooks.
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