U.S. forecasters use the Saffir-Simpson Hurricane Scale for categorizing hurricanes. Generally, damage rises by a factor of four for every category increase. But even the smallest of storms can cause a catastrophe.
Category 1
- Wind: 74-95 mph.
- Surge: 4-5 feet.
- Effects: No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery and trees. Also, some coastal flooding and minor pier damage.
Category 2
- Wind: 96-110 mph.
- Surge: 6-8 feet.
- Effects: Some roofing material, door and window damage. Considerable damage to vegetation, mobile homes. Flooding damages piers and small craft in unprotected moorings may break its moorings.
Category 3
- Wind: 111-130 mph.
- Surge: 9-12 feet.
- Effects: Some structural damage to small residences and utility buildings, with a minor amount of curtain-wall failures. Destruction of mobile homes. Flooding near the coast destroys smaller structures with larger structures damaged by floating debris. Terrain may be flooded well inland.
Category 4
- Wind: 131-155 mph.
- Surge: 13-18 feet.
- Effects: More extensive curtain-wall failures with some complete roof structure failure on small residences. Significant erosion of beach areas. Terrain may be flooded well inland.
Category 5
- Wind: 155 mph and more.
- Surge: 18 feet and more.
- Effects: Complete roof failure on many buildings. Some complete building failures. Flooding causes major damage to lower floors of all structures near the shoreline. Massive evacuation of residential areas may be required.