July to September 2021 rainfall outlook:
Above average July to September rainfall for most of Australia
RAINFALL for July to September is likely to be above average for most of Australia, with the chance of exceeding median greater than 60 percent, and most of the eastern three-quarters of the country is showing a greater than 80pc chance.
Parts of western Wester Australia, southern Victoria and western Tasmania have roughly equal chances of above or below average rainfall (chance of exceeding the median is close to 50pc).
The pattern for July and August are similar to the three month July to September outlook, though the likelihood of exceeding the median rainfall is lower in August.
For the fortnight 5 to 18 July, rainfall is likely to be above average in a band extending from north-west WA through southern parts of the Northern Territory, South Australia, and into southern Queensland, New South Wales, and northern Victoria. Parts of western WA, southern Victoria, western Tasmania, and across the north of Queensland and the Top End in the NT are likely to have near- to below-average rainfall.
Historical accuracy for July to September rainfall is high to very high for most of Australia, with moderate accuracy for parts of western WA and south-east Australia.
It should be noted that the northern Australian dry season commenced in May. This means tropical northern Australia typically has very low rainfall totals, and only a small amount of rainfall is needed to exceed the median.
July 2021 rainfall outlook:
August 2021 rainfall outlook:
‘First look’ August to October 2021 rainfall outlook:
Warmer days for northern tropics, and far south-west and south-east of Australia; warmer nights nationwide
Maximum temperatures for July to September are likely to be above average in northern Australia, and the far south-west and far south-east (greater than 80pc chance). Elsewhere, there are roughly equal chances of above or below average maximum temperatures (chance of exceeding the median is close to 50pc), with some inland areas likely to be below average (chance of exceeding the median 30-40pc chance).
July and August monthly maximum temperatures show a similar pattern to the three month July to September period, although for July the chances are reduced (chance of exceeding the median around 30-40pc).
Minimum temperatures for July to September are very likely to be above average for most of Australia (chances are greater than 80pc).
July and August minimum temperatures show a similar pattern, except for parts of southern WA and the southeast mainland, where the chances of exceeding the median are slightly lower (60-80pc chance).
Historical accuracy for July to September maximum temperatures is moderate to high for most parts of Australia, with low accuracy in central Australia. For minimum temperatures, accuracy is moderate to high for northern and eastern Australia, moderate to low for SA, and low to very low in southern WA.
Maximum temperature outlook July to Sep 2021:
Minimum temperature outlook July to Sep 2021:
Source: Bureau of Meteorology.
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Previous forecast versus actual rainfall
Maps below compare BOM’s rainfall forecast for March to May 2021, issued 25 February 2021, with actual rainfall recorded over the March to May 2021 period.
Forecast median rainfall March to May 2021:
Actual rainfall recorded March to May 2021:
Source: Bureau of Meteorology