Above median spring rainfall likely for eastern two-thirds of Australia
RAINFALL for spring (September to November) is likely to be above median for south-east Western Australia, the Northern Territory, South Australia, Queensland, New South Wales, Victoria and eastern Tasmania, with a greater than 60 percent chance of exceeding the median. Much of the eastern states show a greater than 80pc chance, as does eastern parts of the NT and SA. Conversely, parts of western WA and south-west Tasmania are likely to have below median rainfall, with a less than 40pc chance of exceeding the median.
The pattern for the months of September and October is similar to the spring outlook, though the likelihood of exceeding the median rainfall is not as high in the eastern two-thirds of the country, and extends further west into eastern WA for September.
Rainfall for October to December is likely to be above median for the eastern half of Australia, and below median for north-west WA.
Past accuracy for September to November rainfall is high to very high for most of the eastern two-thirds of Australia, with moderate accuracy for central and eastern Victoria, most of WA and the central NT shifting to low accuracy for central areas of WA.
September 2021 rainfall outlook:
October 2021 rainfall outlook:
Warmer spring days for the northern tropics and far south-eastern Australia, but cooler for parts of southern and eastern Australia; warmer nights nationwide, except for southern Western Australia.
Maximum temperatures for September to November are likely to be above median for northern tropical Australia, coastal parts of southern New South Wales and Victoria, and Tasmania (greater than 60pc chance), with most of these areas very likely to have warmer September to November days (greater than 80pc chance). Below median maximum temperatures are more likely for southern WA, South Australia, south-east Northern Territory, southern Queensland, west of the divide in NSW, and north-west Victoria, with a 30-40pc chance of exceeding the median.
In September, maximum temperatures are likely to be above median for most of the northern half of Australia, western WA, southern and eastern NSW, south-east SA, Victoria and Tasmania (greater than 60pc chance). In October, the warmer pattern retracts, with the far north, and Tasmania likely to be above median, and most of the southern two-thirds of the mainland likely to be below median.
Minimum temperatures for September to November are very likely to be warmer than median for most of Australia (chances are greater than 80pc). However, southern WA has roughly equal chances of above or below median overnight temperatures (chance of exceeding the median is close to 50pc), with the south-west more likely to have below median minimum temperatures.
Likewise, minimum temperatures for September and October are likely to be above median for most areas, with much of southern WA having roughly equal chances of above or below median overnight temperatures. In October, minimum temperatures are likely to be below median for southern WA.
Past accuracy for September to November maximum temperatures is high to very high for almost all of Australia. For minimum temperatures, accuracy is high across the far north, and most of the southern half of Australia, with moderate to low accuracy for southern WA and central SA, and in a band extending from northern WA, through the central and southern NT and across to central Queensland.
Maximum temperature outlook Sep to Nov 2021:
Minimum temperature outlook Sep to Nov 2021:
Source: Bureau of Meteorology.
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Previous forecast versus actual rainfall
Maps below compare BOM’s rainfall forecast for May to July 2021, issued 29 April 2021, with actual rainfall recorded over the May to July 2021 period.
Forecast median rainfall May to July 2021:
Actual rainfall recorded May to July 2021:
Source: Bureau of Meteorology