Catastrophe data company Perils has lifted its loss estimate for October’s floods in NSW, Victoria and Tasmania to $840 million.

The figure is up from last month’s initial estimate of $791 million.

Head of Perils Asia Pacific Darryl Pidcock says unlike record $5 billion-plus floods in Queensland and NSW in the opening months of 2022, the event struck outside densely populated coastal areas. That meant the overall cost was relatively contained.

“The October floods mostly affected inland rural areas and losses to the insurance industry were therefore significantly lower,” he said. "For the affected communities they were still a heavy blow. We therefore hope that our work ... can contribute to a better understanding of flood vulnerabilities.”

From October 12 to 28, a series of low-pressure systems brought heavy rain to inland southeast Australia. These connected with tropical air masses from the north loaded with moisture from unusually warm ocean waters.

This led to storms and intense rainfall over the southern Murray–Darling Basin and Tasmania which fell on already saturated soils and led to extensive riverine flooding in inland regions of the three south-east states, breaking historical records in some areas.

The latest available claims figures for the catastrophe from the Insurance Council of Australia (ICA) show 19,000 claims worth $569 million, with 28% closed.

February’s flood cost $5.72 billion from 280,000 claims, making it Australia’s costliest disaster

Wet conditions experienced in many parts of Australia over the past two years have been driven by La Nina, which generates above-average rainfall across much of northern and eastern Australia.

An updated estimate will be published by Perils in April.