Severe flooding – in central Australia? How a vast humid air mass could soak the desert
- Written by The Conversation
On average, Australia’s driest town, Oodnadatta, gets just 172mm of rain a year. But the small town in inland South Australia is likely to get two years’ worth of rain in a single week.
Rainfall records are likely to topple across inland areas, as rains of 150–300mm are predicted this week, following heavy rains in recent days.
Heavy rains are lashing swathes of arid central Australia, as intensely humid tropical air from the Top End is pushed south. Alice Springs is on flood watch. The Trans-Australian rail line is cut amid track washouts. The Northern Territory’s main highway is closed.
More is to come as extreme rains continue over the driest parts of Australia this week. Severe weather warnings for heavy rain have been issued for parts of Queensland, Northern Territory, New South Wales, South Australia and Victoria. Intense rainfall and damaging winds from localised severe thunderstorms will lead to flash flooding. Flood warnings have been issued for rivers and streams across the entire Lake Eyre Basin. The sheer scale of this event is remarkable – and concerning.
Many remote communities will be cut off for weeks and stock losses are likely to be significant. Western Queensland is already reeling after major floods earlier this year. In coming weeks, floodwaters will engorge rivers flowing to Australia’s lowest point, Kati Thanda-Lake Eyre, which could fill for the second year in a row – a rare occurrence. There’s even a possibility the lake could top its 1974 depth record of 6 metres.
What’s causing this?
In recent days, a very slow-moving tropical low has intensified as it moved southeast through the NT.
On the northern and eastern flanks of this weather system lies an incredibly humid airmass from the oceans off Indonesia. As this saturated air moves south, an upper trough extending into northwest New South Wales is forecast to deepen on Tuesday, increasing the risk of heavy falls.
This combination is a recipe for intense rain. As the strengthening upper trough intersects with the humid tropical airmass, it will push saturated air higher up in the atmosphere. Once high enough, the water vapour will condense and fall as heavy rain.
The warmer the air, the more water it can hold. The tropical low is likely to stay almost stationary over central Australia all week, which means it will dump most of its water before eventually weakening.
Two fillings of Kati Thanda-Lake Eyre?
Since European colonisation, Australia’s largest salt lake has only filled to near or full capacity four times – most recently in 2025.
There’s still water in many parts of Kati Thanda-Lake Eyre from last year’s floodwaters. At last year’s peak, the ephemeral lake covered about 80% of its maximum extent and was just over 2 metres deep in the two deepest parts of the lake, Belt Bay and Madigan Gulf.
As of February 10, many parts of the lake still hold water. These waters came from the torrential rains that hit western Queensland almost a year ago.
In December 2025, Kati Thanda-Lake Eyre still had plenty of water. Different mixes of microbes in the saline water are likely responsible for the different colours in Belt Bay (left) and Madigan Gulf (right).
NASA Earth Observatory
Floodwaters typically take months to snake through the lake’s often-dry inland tributaries. If the lake fills again this year, it will be highly unusual.
That’s because the La Niña climate driver in the Pacific Ocean is rapidly weakening and an El Niño is likely. La Niña years tend to bring colder, wetter conditions to Australia, while El Niño years tend to be hotter and drier.
Until now, every filling of Kati Thanda-Lake Eyre recorded has been linked to strong La Niña years. Last year’s partial filling took place during a moderate La Niña.
It’s getting harder to project what’s likely to happen based on past experience. When the lake filled to a record depth of 6m in 1974, widespread falls of 300–600mm fell on dry catchments. This year, many northern rivers and streams in the Lake Eyre basin were already at minor or moderate flood level before this huge rain-bearing system formed.
Is there a climate change link?
One of the most visible and devastating changes from global heating is what’s happening to the global water cycle, which moves water from lakes and oceans to clouds to rivers, lakes, snow and ice and back again.
Burning fossil fuels and other emissions have made the world 1.48°C hotter than the pre-industrial period. This is already supercharging the water cycle. This is why we’re witnessing extreme rainfall hitting more often and more intensely across the globe.
There’s a clear link between climate change and more extreme rains and floods. For every 1°C of warming, the atmosphere holds 7% more water vapour. But this figure could be even higher for short-duration rainfall, such as during severe thunderstorms.
Without attribution studies, we can’t say this week’s extreme rains have a direct climate change influence. But the overall trends are very clear.
For the dryland and desert towns, communities and stations bracing for impact, this will be small comfort. It’s crucial we don’t underestimate these rains. They are packing a punch.
