‘Astronomical’; the ‘strongest storm in a century’; ‘nearing the mathematical limit for a storm’ – the increasingly fraught descriptions of Hurricane Milton are coming through thick and fast even before it has struck Florida. But how strong is Milton really? The hurricane has been recorded as a category five hurricane – the highest classification – with maximum wind speeds of 180 mph. But it is still out to sea. By the time it makes landfall at the end of the week it is forecast to fall to category three. As for the ‘strongest storm in a century’, it may turn out to be the strongest hurricane to hit Tampa Bay in Florida in 100 years, but not elsewhere. Tampa Bay is not usually struck by hurricanes, which tend to hit the east coast of Florida, rather than the west.
There are different ways of measuring the strength of a hurricane. On maximum measured wind speed Milton in the strongest since Hurricane Rita in 2005. On atmospheric pressure it is the fifth deepest recorded. On the speed of intensification it is the strongest since Wilma in 2005 and Felix in 2007. Much has been made of Milton being the second storm to reach category five this year, but this is not unprecedented. There have been five years which had at least two such storms: 1961, 2005 (which had four), 2007, 2017 and 2019.
All these records need to be read in conjunction with the fact that it is only relatively recently that we started to get detailed data on hurricanes, especially offshore. While we have records on hurricanes dating back 200 years, scientists only started using satellites to measure speed of offshore hurricanes in the 1970s. Therefore, when we read that Milton has been recorded as developing into a category five storm over the Gulf of Mexico, that is something we have only been able to do in the past 50 years. Before that, data on offshore hurricanes is extremely sparse.
Some, including Al Gore, have tried to frighten us with graphs showing a rise in the cost of hurricane damage, but this is pretty meaningless given that property prices have risen considerably over time, as has the area of vulnerable coastline that is developed. What about deaths? The most fatal year was 1900, when there were between 8,000 and 12,000 deaths from hurricanes, followed by 1893 (3,000 deaths) and 1928 (2,500 deaths). The only year this century which makes it into the top ten is 2005, when Hurricane Katrina struck New Orleans, killing 2,067 people. Improved warning systems, together with stronger-built homes, have a lot to do with this – although there are now far more people living in hurricane-prone areas.
Milton is definitely a strong storm and will cause widespread devastation, but that is what happens when a hurricane hits land. As for climate change, the underlying fact is that there has been no increase in the number of landfalling hurricanes in the US in 200 years.
While a higher proportion of hurricanes now seem to make it to categories four and five, we now have much more ability to measure wind speed. While more hurricanes are now recorded across the whole Atlantic basin than 100 years ago, this has a lot to do with better data collection. A century ago a storm which stayed at sea might not have been recorded at all.