Australia's weather bureau has said much of the country will face unusually heavy downpours, confirming that a La Nina weather event was under way for the third year in a row.

Extreme weather in March left at least 13 people dead in Queensland and New South Wales
Extreme weather in March left at least 13 people dead in Queensland and New South Wales (Reuters Archive)

Australia's weather forecaster has warned of potential heavy flooding in parts of New South Wales, as the country braces for heavy rains due to a third straight La Nina weather event.

The Bureau of Meteorology on Saturday issued a warning for flooding in parts of western New South Wales, Australia's most populous state, saying it was possible at the towns of Gunnedah and Wee Waa.

The state's emergency services commissioner, Carlene York, told ABC television on Saturday that 12 flood rescues were made overnight.

READ MORE: Frustration swells in Australia over slow flood relief

"The threat of flooding is real... out there in the community," she said. 

"Weather we have had over the last 12 to 18 months, it’s been relentless rain."

The weather bureau said on Tuesday much of Australia would face unusually heavy downpours in coming months, confirming that a La Nina weather event was under way for the third year in a row, likely lasting into 2023.

La Nina occurs when strong winds blow warm water on the surface of the Pacific Ocean near the South American coast across the equator into Indonesia, other regions of Asia, and Australia.

Rain clouds normally form over warm ocean water, meaning that places like Australia can get much more rain than usual.

Impacts of climate change

Australia has been hard-hit by the impacts of climate change in recent years, enduring floods, searing temperatures, changing fire and rainfall trends, rising sea levels and ocean acidification.

Extreme weather in March left at least 13 people dead and tens of thousands had to evacuates in Queensland and New South Wales, with town centres submerged, homes washed away and power cut.

READ MORE: UN: Humanity going in "wrong direction" on climate crisis

The La Nina event puts the densely populated east coast on alert when many residents are still rebuilding after the floods.

York warned of a more intense storm season from October to March due to greater rains owing to the La Nina weather.

Source: TRTWorld and agencies