Near equal chances of wetter or drier three months for most of Australia
Chances of a wetter or drier October to December for Australia are roughly equal, according to the Bureau of Meteorology’s seasonal climate outlook forecast for October to December, released this morning.
While the overall three-monthly signal is neutral, October is likely to be wetter than average for central and eastern mainland Australia, and drier for western WA. This wet signal is likely to be driven by more localised weather events.
Climate influences from the Indian and Pacific oceans are likely to be competing, with a slightly drying influence in the Indian Ocean likely cancelling out a slightly wetter influence from the Pacific Ocean.
Historical outlook accuracy for October to December is moderate for most of Australia, but low in parts of the southern mainland, southern Queensland and parts of the tropical north. See map for more detail.
This is how the bureau rates the chances for rain across Australia in each of the next three months
October is looking particularly promising for many eastern areas:
November less so:
Warmer three months likely for northern and southeastern Australia
October to December daytime and night-time temperatures are likely to be warmer than average for tropical northern Australia, western WA, the Queensland coast, and parts of southeast Australia. Nights are likely to be cooler around the Great Australian Bight. Elsewhere, chances of warmer or cooler days and nights are roughly equal.
For October, cooler nights are likely for southern WA, most of SA, and western NSW. Warmer October nights are more likely in eastern Victoria, Tasmania and northern Australia.
Historical accuracy for maximum temperatures is moderate to high over most of Australia, except for a small area in western WA, where accuracy is low. Minimum temperature accuracy is moderate over much of the country, but patchy along parts of the east coast and the northern tropics.
Comparison – previous outlook versus actual rainfall
Maps below compare BOM’s rainfall forecast for June to August 2017, released in mid-Mayl 2017, with actual rain that fell over the June to August 2017 period.
Scroll between images below: