For the first time in recorded history, South Australia's Kati Thanda-Lake Eyre is expected to be inundated for a second consecutive year.
Australia's largest salt lake may even top its 1974 depth record of six metres, an expert says.
Warnings remain for catchment rivers and streams across the entire Lake Eyre Basin after a slow moving low pressure system wreaked havoc.
Central Australia is bracing for more wild weather after severe storms and heavy rain hit hard, impacting rail services and cutting off roads and freight deliveries.
In recorded history, Australia's largest salt lake has only filled to near or full capacity four times.
In more than 160 years of data it has never happened two years in a row, CQ University's Steve Turton said.
"It's very interesting, because it could well be that this might be the first time in history that it's filled two years consecutively," the environmental geography professor told AAP.
Weeks of record-breaking rainfall across inland Queensland have saturated catchments, ensuring floodwaters are slowly draining toward Kati Thanda-Lake Eyre.
Parts of the lake still hold water from 2025, Prof Turton said.
The Kati Thanda-Lake Eyre Basin spans almost one-sixth of Australia and four states and territories - SA, the Northern Territory, Queensland, and NSW.
It is one of the world's largest internally draining river systems, meaning its water slowly evaporates.
At its deepest - 15.2 metres below sea level - Kati Thanda-Lake Eyre is the lowest natural place in Australia.
About 400km from the nearest coast, the lake is usually an expanse of dry, crusty white salt, but the region comes alive when water flows.
The eggs of brine shrimp, which remain dormant for years in dry soil, hatch, and the fish flushed through the river systems offer a buffet for birds.
Visitors are already making plans to experience the unprecedented event.
"We're already taking bookings for aerial tours," Tom Noonan, from Lake Eyre tours, told AAP.
"It's fantastic, almost unbelievable. It comes alive with the bird life and the colours.''
Flood warnings remain in place across much of central Australia, including Queensland's northwest, with the Flinders, Cape and Georgina Rivers set to be impacted.
Heavy falls are forecast into the weekend, before the system begins to weaken.
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