The Saffir-Simpson Hurricane Scale

Storm Category  Wind Speed Damage
1 74-95 MPH Minor building damage. Damage primarily to unanchored mobile homes, shrubbery and trees. Some coastal road flooding and minor pier damage.
2 96-110 MPH Some roofing material, door and window damage to buildings; considerable damage to vegetation, mobile homes and piers.
3 111-130 MPH                            
Some structural damage to small residences and utility buildings. Mobile homes are destroyed. Flooding near the coast destroys smaller structures with larger structures damaged by floating debris.
4 131-155 MPH More extensive damage with some complete roof structure failure. Extensive flooding probable requiring massive evacuation of residential areas.
5 155 MPH and higher Extensive complete roof failure and some building failure. Major damage to structures located less than 15 feet above sea level and within 500 yards of shoreline. Massive evacuation of residential areas on low ground within five to ten miles of the shoreline may be required.