Florida residents must feel like they’ve been hit by major hurricanes in recent years, but what does the data show?
The problem with human perception of these things is that the time scale of fluctuating hurricane activity is often much longer than human experience. For example, a person born in the 1950s will have no memory of Florida being hit in the 1940s by major hurricanes (5 in total). But he will have many memories of the hurricane season of the 1970s and 1980s, when each decade had only one hurricane strike Florida. Then, when there is an upswing in hurricane attacks, it seems very unusual to them, and they think that “the storm is getting worse”.
Another problem is that any statistics for a small area like Florida, even over 100+ years, will be very crowded. Storm landfall for the eastern US would be a better metric. And the statistics for the entire Atlantic basin would be better, except that satellite coverage did not begin until the 1970s and the intensity of hurricanes in remote areas before that would be measured (or not measured at all).
Finally, tropical cyclone statistics for all tropical regions would be the best (if one is trying to determine whether climate change is affecting cyclone intensity or frequency). But satellite data for the global tropics are limited to the period since the 1970s. Global tropical cyclone data prior to the 1970s are sketchy, at best.
So, keep in mind that any trends we see in Florida will be heavily influenced by the “luck of the draw” and the quasi-random nature of hurricane tracks (hurricanes driven by large air currents in the mid-troposphere, say around 20,000 ft high or so), what are the statistics of Florida major hurricane intensity and frequency since 1900?
Florida Major Hurricane Intensity & Numbers
The plot below shows the intensity of major hurricanes (100 knots or greater maximum wind speed) that have struck Florida since 1900, updated through Hurricane Helene (2024):
As can be seen from the linear trend line, there is no significant trend in the intensity the worst hurricane to hit Florida since 1900.
But what about number from a hurricane? The next plot shows a slight upward trend in the decadal total of major hurricanes that hit Florida since 1900:
Note that the 2020 number may increase, as the end of the current hurricane season (2024) is only half way through 2020. While Hurricane Milton was recently classified as a major hurricane, within 2 days it is expected to increase, so it is not clear will hit Florida as a major hurricane, so I’m not including it above. chart.
Another feature of the second chart above shows that native Floridians born in the 1960s or 1970s have experienced an increase in major hurricanes hitting Florida during their lifetime. But the first few decades of his personal experience would occur during a historic lull in hurricane activity.
Why Start In 1900?
There is reason to believe that the number and / or intensity of major hurricanes striking Florida in the early 1900s has been underestimated, which will bias the trend in the plot above in an upward direction, spuriously suggesting a long-term increase in activity. First, almost no one lived in Florida in 1900. The population of Miami in 1896 was 444. The intensity of a typhoon is based on the maximum wind speed of 1 minute, which usually covers a very small area. Even with people who now live along many of Florida’s coasts, it is rare for coastal anemometers to measure the intensity that the National Hurricane Center assigns to hurricanes, because the winds cover such a small area. So, how do you know what hurricanes were like in the early 1900s?
You should also remember that not too long ago the US experienced an “unprecedented” 11-year drought in major hurricanes. That significantly affects our understanding of “normal”. When the hiatus reached 9 years, a NASA study found it to be a 1 in 177 year occurrence. As I recall, that increases to 1-in-250 years when the interval reaches 11 years.
The point is that there is a lot of decadal to centennial scale variation in hurricane activity in Florida (or any other hurricane-prone state). But with more and more people thinking that the government has an influence on hurricane activity (I see a lot of this on Twitter), I doubt that the real data will have much of an impact on them, and as I approach my 70 years on this Earth. I have seen a long-term decline in critical thinking about weather, climate, and causality. I doubt the trend will change anytime soon.
