The Insurance Council last night released its provisional figures for the flooding, revealing damage to more than 2000 homes and $20.86 million of damage to insured property.
The storm, from July 20 to 22, brought more than 100mm of rain in 24 hours to much of Otago and Canterbury and caused flooding in settlements south of Dunedin as well as Christchurch and Timaru.
In addition, rain caused millions of dollars of damage to the areas' roading networks because of slips and other issues.
Last week, the Dunedin City Council and Otago Regional Council said the event had cost them more than $2 million combined so far, while the NZ Transport Agency said damage to its network had cost $2.6 million in Otago.
The rain came on the back of a nationwide cold snap from July 12 to 14 which brought snow, wind and rain to the country and caused more than $10 million in damage.
Insurance Council chief executive Tim Grafton said the $30 million month had contributed to 2017 being the costliest in the council's history for weather damage, even with three months left.
''The two July weather events bring the total for significant weather events for 2017 to $230.2 million, which now surpasses the year of the Wahine storm in 1968.''
While the council did not break down regional figures for the July 20-22 storm, provisional figures showed 2208 homes, 433 commercial premises and 269 motor vehicles were damaged.
It is the costliest weather damage in the region since June 2015's deluge caused $28 million of damage, much of it in the heavily populated and condensed area of South Dunedin.
