Climate outlook for December to March
Climate outlook overview
- December to February rainfall is likely to be above average across much of Australia.
- Maximum temperatures averaged over December to February are likely to be above the long-term mean for parts of southeast and far west Australia, as well as along the Queensland coastline.
- Minimum temperatures averaged over December to February are very likely to be above the long-term mean across much of Australia.
- La Niña is underway in the tropical Pacific. La Niña typically increases the likelihood of above average rainfall across eastern Australia during summer.
December to February wetter than average for much of Australia
- December to February is likely to be wetter than average for much of Australia (greater than 75% for northwest Australia, eastern Queensland and along the NSW coast, greater than 60 % chance for most remaining parts of the country). For Tasmania, roughly equal chances of wetter or drier conditions are more likely. A similar outlook exists for December though the likelihood of above average rainfall is increased over western Australia and decreased over southeast Australia.
- The fortnight 7 to 20 December is likely to be wetter than average for most of tropical Australia (greater than 80% chance), as well as most of southern WA and northeast NSW (greater than 60% chance). Drier than average conditions are more likely along the west coast of Tasmania (greater than 60% chance).
- While the outlooks indicate wetter than average conditions, southern parts of Australia are entering into their drier season, so rainfall is not likely to be sufficient to relieve long-term rainfall deficits.
Warmer days for the far north, far west and parts of the southeast from December to February; warmer nights very likely for most of Australia
- Averaged over the fortnight 7 to 20 December, maximum temperatures are likely to be above the long-term mean for southeast Australia, far west WA and the Queensland coast (greater than 70% chance). Below average maximum temperatures are more likely over eastern QLD, NT and the remainder of WA. Minimum temperatures averaged over this period are likely to be above the long-term mean across most of Australia (greater than 70% chance), except over the eastern interior of WA and adjacent NT where roughly equal chances of warmer or cooler minimum temperatures are more likely.
- Maximum temperatures averaged over December to February are likely to be higher than the long-term mean for Tasmania, far west WA and along the coastlines of NT and QLD (greater than 70% chance), as well as for most of Victoria and southeast SA (greater than 60% chance). Below average maximum temperatures are more likely across eastern WA and adjacent NT (greater than 60% chance).
- Minimum temperatures averaged over December to February are very likely (greater than 80% chance) to be higher than the long-term mean across most of Australia, apart from over the eastern interior of WA and adjacent parts of NT and SA where the chance is closer to 60%.
Climate influences
- The Bureau's ENSO Outlook is at La Niña indicating that La Niña remains active in the tropical Pacific Ocean.
- Model outlooks suggest the La Niña will peak around December or January and is likely to persist until at least the end of February 2021.
- Warmer sea surface temperatures to the north of Australia are likely to persist through December and contribute to the wetter outlook for this month.
- The Southern Annular Mode (SAM) is neutral but is forecast to return to more positive values over the next fortnight. La Niña and a strong polar vortex favour a positive SAM, with generally positive values expected over the 2020–21 summer. This typically enhances the wet signal of La Niña in parts of eastern Australia, although western Tasmania is typically drier.
- The Indian Ocean Dipole (IOD) is neutral. During December to April, the Indian Ocean Dipole typically has little effect on Australian climate.
- Australia's temperature and rainfall variability are also influenced by global warming caused by human activities. Australia's climate has warmed by 1.44 ± 0.24 °C since 1910 while recent decades have seen increased rainfall during the northern wet season (October–April), with more high intensity and short duration rainfall events.
- 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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