Climate outlook for October to January
Climate outlook overview
- The remainder of the year is likely to see above average rainfall across the eastern two thirds of the country.
- October to December days are likely to be warmer than average across parts of northern Australia, and the far south-east, but cooler than average in southern WA.
- Nights during October to December are very likely to be warmer than average across much of Australia.
- The Bureau's ENSO Outlook is now at La Niña, meaning a La Niña is underway in the tropical Pacific.
- The Indian Ocean Dipole (IOD) index is within negative threshold values with most models sustaining these negative values into October.
- La Niña and a negative IOD typically increase the likelihood of above average rainfall across much of Australia during spring and early summer.
Wet end to 2020 for much of Australia
- October to December is likely to be wetter than average for much of mainland Australia and north-east Tasmania (greater than 75% chance in much of this area).
- Chances of a wetter or drier than average three months are roughly equal for much of north-west WA while drier than average conditions are more likely in south-west Tasmania.
- October is likely (greater than 65%) to see above average rainfall across much of the eastern two thirds of the mainland and north-east Tasmania. Western WA and some coastal regions in the east of the country have roughly equal chances of a wetter or drier than average October while drier than average conditions are more likely in south-west Tasmania.
- In the shorter term, the fortnight 5–18 October is likely to be wetter than average for the eastern Queensland tropical coast as well as a band extending from the Kimberley and the NT, into central Australia and much of SA and NSW. Parts of south-west Tasmania are likely to be drier than average.
Warmer days on the northern coasts and far south-east for the remainder of 2020; warmer nights likely
- In the short-term, daytime temperatures for the fortnight 5–18 October are likely to be above average for much of northern, eastern and south-east Australia. Chances of warmer or cooler days are roughly equal for western and southern WA, western SA and along the eastern Queensland coast. Nights during this period are likely or very likely to be warmer across Australia apart from south-west WA where closer to average conditions are more likely.
- For the remainder of 2020, days are very likely (greater than 80% chance) to be warmer than average along the far northern Australia coast and over the far south-east of the country. Warmer than average conditions are also likely (60 to 75% chance) for parts of northern Australia while cooler than average days are more likely towards southern WA. A similar outlook exists for October, with warmer than average days also likely over most parts of central and south-east Australia.
- Nights are very likely (greater than 80% chance) to be warmer than average for most of Australia for the remainder of 2020, though the likelihood is reduced over south-west WA (closer to 60 to 70% chance).
- The Bureau's ENSO Outlook is now at La Niña, meaning a La Niña is underway in the tropical Pacific Ocean.
- All eight surveyed international climate models, including the Bureau's model, anticipate La Niña conditions are likely to persist until at least January 2021.
- The Indian Ocean Dipole (IOD) index is currently within negative IOD thresholds.
- Most models suggest the IOD index will continue to meet negative IOD thresholds during October, with several maintaining these values into November. It is unclear at this stage whether these negative values will be sustained for long enough to be considered a negative IOD event.
- The Southern Annular Mode (SAM) is currently negative but is expected to increase to weakly positive values in the coming week. Positive SAM during spring is typically associated with wetter and cooler than average conditions in parts of eastern Australia.
- Australia's temperature and rainfall variability are also influenced by global warming caused by human activities. Australia's climate has warmed by around 1.4 °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 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.
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