Costliest tropical cyclone (inflation-adjusted)

The costliest tropical cyclone when adjusted for inflation is Hurricane Katrina, which struck the southern United States between 23 and 31 August 2005. According to figures compiled by the NOAA, Katrina caused damages totalling $125 billion, or $161.3 billion in 2017 dollars (calculated using the US Consumer Price Index). This exceeds the $125 billion and $90 billion in damages caused by 2017's Hurricane Harvey and Hurricane Maria respectively.

It should be noted that the NOAA only keeps detailed records on damages going back as far as 1980. Shifting economic trends (value of land and other property, patterns of insurance, population density, etc.) make it difficult to compare older storms using CPI inflation alone. Some studies using a technique called "wealth normalisation", which models the cost of damages if the same storm were to strike the same area in the present day, produce slightly different results. According to a paper published in 2006 by an international group of researchers, the Great Miami Hurricane – which struck southern Florida on 18 September 1926 - edges out Katrina with a wealth-normalised (to 2006 dollars) cost of around $157 billion.

These same underlying economic and social conditions are the reason why the costliest tropical storms are all in the United States. While powerful storms like Typhoon Haiyan and Typhoon Megi caused considerable damage and many deaths in the Philippines, the low level of economic development there limited the reconstruction cost of these storms to a fraction of what it would have been if a similar storm had struck the US. Japan, which has comparable economic development and population density is too far north to get more than glancing blows from typhoons, and the parts of Australia that are at risk of tropical cyclone damage are very sparsely populated.