Parts of northern NSW received 60% of their annual rainfall totals in the space of a week at the height of February's flood disaster.
From February 22 to March 9, a combination of weather systems collided to dump a record-breaking amount of rain on already saturated catchments from south-east Queensland and through eastern NSW.
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More than 50 sites recorded over one metre of rainfall in one week.
For north-east NSW, this was the wettest week since at least 1900 and several records tumbled along with it.
Details of the weather event were revealed in the Bureau of Meteorology's Special Climate Statement 76 which was released on Wednesday.
"What was really unusual about this event was the multi-day rainfall totals. There were really high rainfall rates in some locations," said the BOM's national manager of climate services, Karl Vraganza.
"Extra heavy rainfall is a natural feature of climate systems in that region.
"This broke existing records, is the best way to describe it.
"What we saw was really substantial rainfall over a five-day period. There was a lot of water. Over a metre of water in some catchments."
Those expecting to see a break in the weather pattern over the second half of the year might be disappointed.
"Unfortunately, wet conditions are expected for the next few months," he said.
The BOM's special weather statement looked into the extreme rainfall and flooding in south-eastern Queensland and eastern New South Wales in February and March this year.
Devastating flooding occurred through Lismore (Wilsons River) and other nearby towns, including Coraki and Woodburn (Richmond River) and Murwillumbah and Tumbulgum (Tweed River).
For the seven-day period ending March 1, the Upper North Coast rainfall district, which covers the Northern Rivers, had its wettest week since at least 1900, with an area-averaged rainfall total of 642.8 mm, exceeding the previous record set in March 1974 of 480.3 mm.
This region also broke its previous area-averaged rainfall records for the single daily rainfall total (since 1900), and for multi-day totals of two, three, five, six and seven days.
The weekly rainfall totals in parts of north-east New South Wales were in excess of 60% of the average annual total rainfall (based on the 1961-1990 period), with a broader region receiving more than 40% of the average annual total rainfall.
Following two years of La Nina conditions, the rain fell on catchments that were already wet, so water storages and river levels were high and catchments quickly became saturated.
The highest seven-day total recorded in eastern NSW was 1,346 mm at the flood warning site at Uki on the Tweed River.
The highest total reported in near-real time in the Bureau standard network was 1,090.6 mm at Rosebank.
Lismore, located at the junction of Leycester Creek and Wilsons River, suffered devastating flooding on February 28.
The Wilsons River at Lismore peaked at a record high level at 14.4 metres between 1pm and 3pm on February 28, overtopping the riverbank levee (10.6 metres) with floodwaters inundating the city.
This exceeded the previous record flood level (12.27 metres in February 1954) by over two metres.
Heavy rainfall also caused record major flooding along the Richmond and Tweed rivers. Levels of the Richmond River at Woodburn peaked at 7.17 metres on March 1, well above the major flood level of 4.2 metres and exceeding the February 1954 peak (5.42 metres) by around 1.8 metres.
The Richmond River at Coraki peaked at 7.65 metres on March 1, higher than the March 1974 peak (7.01 metres).
I'm a media professional with over 34 years of experience in public relations and journalism, including a decade setting Lismore's news agenda as the editor of The Northern Star. I have proven track record in growing audiences and improving engagement by delivering quality local stories for and about the Lismore community.
I'm a media professional with over 34 years of experience in public relations and journalism, including a decade setting Lismore's news agenda as the editor of The Northern Star. I have proven track record in growing audiences and improving engagement by delivering quality local stories for and about the Lismore community.
