The Bureau of Meteorology has today released a special update to the three month climate outlook for October to December 2015 issued last week, after recognising a significant shift towards stronger El Nino conditions.
September rainfall was third driest on record for Australia. Very low rainfall has been received over the past 12 months in the southwest of Western Australia, southeast South Australia and most of Victoria.
Due to changed conditions in the tropical Indian Ocean and the strong 2015 El Niño, the rainfall outlook for October has shown a significant shift towards a drier month nation-wide, with the southeast quarter of Australia indicating a less than 20% chance of exceeding median rainfall for the month. This means the region has a greater than 80% chance of a drier month.
The October rainfall outlook is accompanied with high chances of warmer days and nights south of the tropics.
October to December is likely to be drier than average across the southeast and northeast, with parts of central Australia likely to be wetter than average. Warmer days and nights are likely for Australia, except the northern tropics.
The current outlook reflects a combination of a mature El Niño in the Pacific, and an emerging positive Indian Ocean Dipole.
The specific outlook for October shows a notable shift – up to 40 percentage point decrease in some areas – towards a drier month nation-wide, with the southeast quarter of Australia indicating a less than 20% chance of exceeding median rainfall. This means the region has a greater than 80% chance of a drier month.
October to December is likely to be drier than average across southeast and northeast Australia. Conversely, eastern parts of WA, and southern parts of the NT show a slightly increased chance of a wetter three months.
Historical outlook accuracy for October to December is moderate over most of Australia.
Daytime temperatures for October to December are likely to be warmer than average across the southern half of Australia, extending into central Queensland. Daytime temperatures are likely to be cooler than average in an area spanning northern WA and the central NT.
Overnight temperatures are likely to be warmer than normal across much of the country except in parts of the tropical north which has an increased chance of cooler nights. Across large parts of southern Australia, there is a strong likelihood of above average night-time temperatures (greater than 80% chance).
Maximum temperature accuracy is moderate to high over most of Australia, except for a small area in far west WA, where accuracy is low. Minimum temperature accuracy is moderate to high over much of the country but patchy in the northern tropics, and parts of the east coast.