Climate outlook for May to August

Climate outlook overview

  • Wetter than average conditions are likely for most of Australia during the remainder of autumn and into winter. The exception is parts of the tropical north and along the eastern seaboard, where outlooks have roughly equal chances of being wetter or drier than average. 
  • May to July days are likely to be warmer than average across northern Australia and the eastern seaboard, but cooler than average across inland areas of the southern mainland. 
  • Nights for May to July are very likely to be warmer than average nationwide.
  • A warmer than usual eastern Indian Ocean is currently the main influence on Australia's climate, increasing moisture feeding into weather systems as they sweep across the country.

Wetter May to July for most of Australia

  • The fortnight of 13–26 April is likely to be wetter than average for northwest, central, inland eastern and southeastern Australia (mostly 60–75% chance). Southwest WA and Cape York Peninsula in Queensland are likely to be drier than average (60–75% chance).
  • Similarly, the three months May to July are also likely to be wetter than average for most of Australia (60–75% chance). The likelihood of a wetter or drier May to July is roughly equal across the far north NT and Queenland, along the east coast of the mainland, and southern Tasmania.
  • June to August is also likely to be wetter than average for much of Australia (mostly 60–75% chance). 

Warmer May to July days for north and east; cooler for southern mainland Australia

  • May to July days are very likely to be warmer than average in northern Australia and east of the Great Dividing Range (greater than 80% chance for the tropical north, 60–80% elsewhere). In contrast, with more cloud and rainfall than normal expected, days are likely to be cooler than average in the south to the west of the Great Dividing Range (60–70% chance).
  • May to July night-time temperatures are very likely to be warmer than average for most of Australia (70–80% chance for southern Australia, greater than 80% chance elsewhere).

Climate influences

  • A warmer than normal eastern Indian Ocean is increasing the likelihood of northwest cloudbands interacting with fronts and troughs bearing rain as they sweep across the country this autumn and winter. A warm eastern Indian Ocean often occurs after a strong positive Indian Ocean Dipole (IOD) event, like the strong event that occurred recently during the second half of 2019. 
  • While the Indian Ocean Dipole (IOD) is currently neutral, some models indicate it is possible that a negative IOD could develop later this year. Caution should be exercised with using IOD forecasts at this time of year, as they are less accurate than forecasts made at other times of the year. Negative IOD events typically increase the chance of rainfall across southern Australia during winter and spring. 
  • The El Niño–Southern Oscillation (ENSO) is forecast to remain neutral over winter, though a weak La Niña can't be ruled out in 2020.
  • The Southern Annual Mode (SAM) is currently neutral, and likely to remain neutral for the coming three weeks. At this time of the year, SAM has little influence on Australian rainfall.
  • 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 10–15% 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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