THE BUREAU of Meteorology (BOM) has confirmed the heavy rain that caused extensive flooding in Queensland and NSW earlier in the year was record-breaking for many centres.
The BOM issued a special report into the specifics of the flood inducing rain that fell between February 22 and March 9.
Incredibly over 50 sites, primarily through south-eastern Queensland and northern NSW on the coastal side of the Great Dividing Range, received over a metre (1000mm) in a week.
The volume of rain was so intense that parts of south-east Queensland and north-east New South Wales, both high rainfall environments meaning data cannot be easily skewed, had rainfall 2.5 times their monthly average with some regions recording more than five times their monthly average.
The intensity of the flooding was partially due to the volume of rain in the event but also due to the saturated catchment, which had already received heavy La Nina induced rainfall for the past two years, leading to severe flooding from Maryborough in Queensland to Grafton in New South Wales.
Rainfall of this magnitude had not been seen in many areas since at least 1900, especially in northern NSW.
For some areas of south-eastern Queensland there were the highest flood peaks since 1893, though the lower Brisbane and Bremer rivers and Lockyer Creek peaked below the levels of both January 1974 and January 2011 floods.
In parts of northern New South Wales, flood levels broke previous records.
Wilsons River in Lismore peaked at a record high level, estimated to be 14.4 m on 28 February, while Tumbulgum and Coraki were also hard hit by flooding.
The previous record was 12.27 m in February 1954.
Further south it was the biggest flood in the Hawkesbury / Nepean river systems since at least 1900.
In terms of the climate drivers behind the unusually heavy rainfall, a combination of weather systems over eastern Australia and the Tasman Sea, where a large volume of humid tropical air moving onshore over eastern Australia was lifted in the atmosphere to produce heavy rain and thunderstorms.
A blocking high pressure system over New Zealand stopped the system moving east like it normally would.
The BOM said it was just the latest of a number of high intensity rainfall events in recent years, especially across northern Australia.