This made me interested as well. Why the exact cut-offs, right? I found few resources like NOAA https://www.nhc.noaa.gov/pdf/sshws.pdf https://www.nhc.noaa.gov

This made me interested as well. Why the exact cut-offs, right? I found few resources like NOAA https://www.nhc.noaa.gov/pdf/sshws.pdf https://www.nhc.noaa.gov/pdf/sshws.pdf and wikipedia https://en.wikipedia.org/wiki/Saffir%E2%80%93Simpson_scale https://en.wikipedia.org/wiki/Saffir%E2%80%93Simpson_scale saying basically about the wind speed that the actual wind speed is "sustained winds as average winds over a period of one minute, measured at the same 33 ft (10.1 m) height" and then I thought ok if this scalar we're using is correlated to potential damage, that would mean force, right? They did remove air pressure and storm surges as components later on. I didn't bother with air pressure outside of standard since it would deviate a lot into researching exactly that. Since it's not really my domain, I decided to wing it by googling around and looked for wind force formulas. One that I found out ( https://sites.uci.edu/energyobserver/2017/09/07/hurricane-wind-force-increases-as-the-square-of-the-velocity/#:~:text=The%20Force%20on%20a%20unit,F%20%3D%20r%20V%5E2 https://sites.uci.edu/energyobserver/2017/09/07/hurricane-wi.... ) can roughly be translated as F = v^2 but then when I charted it out with x being wind speed and y proportional force, only thing I found out was that it looked logarithmic (which I didn't need a chart for lol ). The other I found was saying for wind load formula "The generic formula for wind load is F = A x P x Cd where F is the force or wind load, A is the projected area of the object, P is the wind pressure, and Cd is the drag coefficient." I had to hunt for variables here, but gist of it is that since scale is in mph I went USA with 1 square foot for A - area (and then to square meters from that, 0,093 m^2), wind speed to m/s, and went with these (more googling): Wind Pressure (P) is P = 0.5 x p x V^2 where p (rho actually) is air density (google: 1.225 kg/m^3 at sea level and 15C, I couldn't find one at 10m height), V is our wind speed, and Cd (drag coefficient) for a flat plate which is 1.28 according to https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/airplane/shaped.html#:~:text=A%20flat%20plate%20has%20Cd,07%20to%20 https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/a.... tl;dr; I couldn't find clear cuts in Newtons. I tried minimum, maximum and average wind speeds for each categories, and then I kind of lost interest there. More googling says that it was based on established observations what wind force can do to structures, but no more than that and I couldn't source original work to see more details. Outside of optics, this is as far as my physics will lead me tonight. I'd be highly interested to see if anyone more in the know can provide methodology behind it, be it from meteorology, construction, or fluid dynamics.