Welcome to the Bureau's long-range forecast for Autumn 2023.
It's likely to be drier and warmer than usual across most of Australia over the coming months.
It's still the wet season in the north, so tropical cyclones remain a risk.
First, let's look at recent conditions.
Summer was much wetter than average across northern Australia.
Five sites in northern Cape York had their wettest summer on record,
2 of which have more than 100 years of data.
Ex-Tropical Cyclone Ellie brought flooding rains to
parts of the Northern Territory and the Kimberley in Western Australia.
In contrast, parts of southern Australia had below average rainfall.
This includes the Murray–Darling Basin which had nearly 40% below average rainfall this summer.
Significant fires have followed dry conditions in the south-west
of Western Australia and in southern Queensland.
While summer was hot in parts of the west and warm in Tasmania,
it was a milder summer than usual for much of northern and eastern Australia.
Sydney's top temperature for summer was only 30.6 °C, the coolest of any capital city.
This last occurred in the La Niña summer of 2011–12.
Overall, Australia's temperature was 0.07 degrees Celsius above the summer average.
After plentiful rain in 2022, soils remain wetter than usual in the north and some central areas.
However, dry soils are emerging in areas of ongoing below average rainfall,
with particularly rapid drying in parts of the northern Murray–Darling Basin.
Despite some drier conditions over summer, water storages remain higher than at this
time last year. Most storages remain at more than 90% full.
The notable exceptions are western Tasmania and the south-west coast
of Western Australia which are both down to around 50% capacity.
So what's likely to influence our climate over the coming months?
La Niña is nearing its end after 3 consecutive wet
years. And there is no record of 4 years of La Niña in a row.
Other climate drivers, including the Indian Ocean Dipole and ocean
temperatures around northern Australia, are also likely to be neutral during autumn.
Rainfall between April and October has been declining
across southern Australia in recent decades.
So what does this mean for the autumn forecast…
Autumn is likely to be drier than normal for much of Australia.
This is the driest autumn outlook for eastern Australia since 2019.
Parts of inland Australia have at least double the normal chance of being unusually dry.
The Autumn Break is the first significant rainfall to help start the crop and pasture
growing season in the south – this year the break is likely to be later than normal.
Higher than usual streamflows are forecast in the south-east and across areas of the north.
The northern wet season continues. Any tropical cyclones and lows that
develop have potential to bring significant rain.
This means the risk of flooding remains in areas where soils are still wet,
rivers are high and dams are full.
Warmer days than usual are likely for most areas, particularly in the far west and in Tasmania.
The autumn bushfire outlook from Australia's fire agencies shows
above normal fire potential for parts of New South Wales, Queensland and Western Australia.
Some areas in the east have below normal fire potential.
Destructive fires can still occur in autumn. Some areas with a lot of vegetation growth
after the wet spring, have dried out over the summer, providing fuel for grass fires.
So, in summary, this autumn we're likely to see: Below average rainfall in most areas,
Warmer days, Above normal bushfire potential for some areas,
AND a continued chance of tropical cyclones, storms and flooding.
You can find the latest long-range forecasts and warnings on the Bureau's website.
Bye for now.