The Saffir-Simpson scale, category by category
The Saffir-Simpson scale sorts hurricanes into five categories by their maximum sustained wind speed. These are the current NOAA thresholds (2021 revision):
| Category | mph | km/h |
|---|---|---|
| Category 1 | 74–95 | 119–153 |
| Category 2 | 96–110 | 154–177 |
| Category 3 (major) | 111–129 | 178–208 |
| Category 4 | 130–156 | 209–251 |
| Category 5 | 157+ | 252+ |
Why a Category 5 is far worse than a Category 3
Damage doesn't rise in step with wind speed — it climbs with roughly the cube of it. The power a wind dissipates scales as speed³, so a small jump in category means a large jump in destructive energy. That's why this tool compares two storms by wind³ rather than by the category number alone. A Category 5 at its 157 mph floor releases about 1.8 times the energy of a Category 4 minimum, and many times that of a Category 3.
For the full story — how the scale was built, what each category does and its limits — read How the Saffir-Simpson Hurricane Scale Works.
Frequently asked questions
What is the Saffir-Simpson scale?
A 1 to 5 scale that rates hurricanes by their maximum sustained wind speed, from Category 1 (74 mph) to Category 5 (157 mph or more). It measures wind damage potential, not storm surge or rainfall.
What wind speed is a Category 5?
157 mph (252 km/h) or higher, sustained for at least one minute. There is no upper bound — a Category 5 can be far stronger than that floor.
Why doesn't damage double when the wind doubles?
Because destructive energy scales with the cube of wind speed. Doubling the wind multiplies the dissipated power roughly eightfold, so damage grows much faster than the wind number suggests.
Is a Category 3 much weaker than a Category 5?
Yes. Measured by wind³, a Category 5 at 157 mph carries roughly 1.8 times the energy of a Category 4 minimum and far more than a Category 3, even though the numbers look close.
Does the scale include rain or flooding?
No. It rates sustained wind only. Storm surge, rainfall and inland flooding can make a lower-category storm deadlier than its number implies.