Climate outlook for January to April
Climate outlook overview
- The Christmas–New Year period is likely to be drier than average for much of the north and east, and wetter in the west. January to March 2020 sees a reduction in the likelihood of drier conditions, with most of the country having roughly equal chances of a wetter or drier than average three months.
- January to March 2020 daytime temperatures are likely to be above average across Australia.
- January to March 2020 nights are likely to be warmer than average for Australia, except parts of southeast Australia.
- The positive Indian Ocean Dipole (IOD) is weakening and will likely end in early January, while the negative Southern Annular Mode (SAM) is likely to persist until the end of December and then rapidly decay.
Mostly neutral rainfall outlook for January to March
- While the fortnight covering the Christmas–New Year period (23 December to 5 January) suggests drier than average weather for parts of the Top End of the NT, northern and eastern Queensland, southern NSW, Victoria, and Tasmania, wetter than average conditions are likely in most of WA, the western NT and western SA.
- The rainfall outlook for January to March 2020 indicates most of the country will have roughly equal chances of a wetter or drier than average three months. Parts of Cape York Peninsula are likely to be drier than average, and most of the Top End of the NT is likely to be wetter than average.
- While outlooks for drier than average conditions 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 early 2020
- 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 the east and the north. 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 and parts of the southeast mainland coast. Chances of warmer nights are very high (greater than 80%) for most of Australia, with chances reducing slightly in the south to southeast.
- The positive Indian Ocean Dipole (IOD) is currently at moderate levels but is weakening. Current forecasts indicate it is likely to end by early January—approximately a month later than normal. 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 the late movement of the monsoon into the southern hemisphere.
- A negative phase of the Southern Annular Mode (SAM) may last until the end of December and then rapidly decay. 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 into 2020, and will have a limited influence on Australian climate.
- Abnormally warm sea surface temperatures in the western tropical Pacific Ocean and to the west of Australia may also be contributing to some changes in weather patterns over Australia.
- With the two major drying climate influences easing by early January, and no other clear climate drivers in play at the moment, the rainfall outlook has little to no climate influence pushing it towards significantly wetter or drier than average.
- 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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