Above median August to October rainfall for most of Australia, but below median for parts of western WA
RAINFALL for August to October is likely to be above median for most of Australia (chance of exceeding median is greater than 60 percent), with most of the eastern two-thirds of the mainland showing a greater than 80pc chance.
Parts of southern Victoria and southern Tasmania have roughly equal chances of above or below median rainfall (chance of exceeding the median is close to 50pc), while parts of western Western Australia are likely to have below median rainfall (chance of exceeding the median is less than 40pc).
The pattern for the months of August and September is similar to the August to October outlook, though the likelihood of exceeding the median rainfall is not as high.
Historical accuracy for August to October rainfall is high to very high for most of Australia, with moderate accuracy for parts of southern and central WA, and south-eastern Australia.
August 2021 rainfall outlook:
September 2021 rainfall outlook:
‘First look’ September to November 2021 rainfall outlook:
Warmer days for the northern tropics and south-eastern Australia; warmer nights almost nationwide
Maximum temperatures for August to October are likely to be above median for tropical northern Australia, far south-east South Australia, most of Victoria, south-east and coastal New South Wales, and Tasmania (greater than 60pc chance), with most of these areas very likely to have warmer August to October days (greater than 80pc chance). Below median daytime temperatures are more likely for areas just west of the Great Dividing Range in NSW, extending into central western parts (chance of exceeding the median is 30 to 40pc).
August and September show a similar pattern, although warmer days are also more likely down the east coast in August, and down the west coast in September.
Minimum temperatures for August to October are very likely to be warmer than median for most of Australia (chances are greater than 80pc). However, south-west WA has roughly equal chances of above or below median overnight temperatures (chance of exceeding the median is close to 50pc).
Likewise, minimum temperatures for August and September are likely to be above median for most areas, with south-west WA having roughly equal chances of above or below median overnight temperatures.
Historical accuracy for August to October maximum temperatures is high to very high for most parts of Australia, with moderate accuracy in parts of the southern mainland and north-west Australia. For minimum temperatures, accuracy is high to very high across most areas, but generally moderate accuracy in north-west Australia and low to very low accuracy across southern parts of the mainland.
Maximum temperature outlook Aug to Oct 2021:
Minimum temperature outlook Aug to Oct 2021:
Source: Bureau of Meteorology.
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Previous forecast versus actual rainfall
Maps below compare BOM’s rainfall forecast for April to June 2021, issued 25 March 2021, with actual rainfall recorded over the April to June 2021 period.
Forecast median rainfall April to June 2021:
Actual rainfall recorded April to June 2021:
Source: Bureau of Meteorology