Climate outlook for January to April
Climate outlook overview
- Remainder of December very likely to be drier than average for many areas, with January 2020 likely to be drier for parts of eastern Australia.
- January to March 2020 daytime temperatures likely to be above average across Australia.
- January to March 2020 nights very likely to be warmer than average for Australia, except parts of Tasmania.
- Climate influences—the positive Indian Ocean Dipole (IOD) is weakening and will likely end in January, while the negative Southern Annular Mode (SAM) is likely to persist into early January.
Mostly neutral outlook for January to March
- While the remainder of December is likely to be drier than average for the NT, Queensland, eastern SA, NSW, Victoria, Tasmania and southwest WA, the rainfall outlook for January 2020 suggests the area of drier conditions will contract to small parts of the east, including Tasmania.
- The outlook for the fortnight covering the Christmas–New Year period (23 December to 5 January) suggests drier than normal conditions for much of the eastern two thirds of the continent.
- The rainfall outlook for January to March suggests only small areas of the southeast and northeast are likely to be drier than average, with some small scattered areas of the northwest likely to be wetter than average. However, much of Australia has roughly equal chances of being wetter or drier than average for January to March.
- While outlooks for drier than average conditions may ease heading into 2020, several months of above average rainfall would be needed to see a recovery from current long-term rainfall deficiencies.
Warmer days and nights likely for January to March
- For the fortnight covering the Christmas–New Year period (23 December to 5 January), days are likely to be warmer than average across most of the country, with much of NSW, Queensland and the eastern NT likely to see temperatures two to four degrees above average for the fortnight.
- Daytime temperatures for January to March 2020 are likely to be warmer than average for Australia, with very high chances across much of north, east, west, and central regions. February to April is also likely to be warmer than average Australia wide.
- Warmer nights are likely for most of the country for January to March except southern and western Tasmania. Chances are very high (greater than 80%) for most of Australia, with chances reducing slightly in the southeast.
- The positive Indian Ocean Dipole (IOD) remains active but is weakening. Current forecasts indicate it is likely to dissipate by mid-summer. Typically, a positive IOD means below average rainfall for much of central and southern Australia, and warmer than average temperatures for the southern two thirds of Australia.
- It is unusual for the IOD to persist far into summer, as it normally breaks down when the monsoon moves into the southern hemisphere in late spring or early summer. The 2019 event has been exceptionally strong, and its decay hampered by a late movement of the monsoon into the southern hemisphere.
- A negative phase of the Southern Annular Mode (SAM) is expected to continue into early January. A negative SAM in summer tends to bring warmer and drier conditions to parts of eastern Australia, but wetter conditions to western Tasmania.
- While tropical Pacific Ocean temperatures are likely to stay warmer than average, the El Niño–Southern Oscillation (ENSO) is expected to remain neutral until at least early 2020, and therefore will have a reduced influence on Australian climate.
- Abnormally warm sea surface temperatures in the western tropical Pacific Ocean may be contributing to some changes in weather patterns over the region.
- In addition to the natural drivers such as ENSO and the IOD, Australian climate patterns are being influenced by the long-term increasing trend in global air and ocean temperatures.
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