The Saffir-Simpson Scale

Tropical cyclones with maximum sustained surface winds of less than 39 mph (34 kt or 61 km/hr) are called tropical depressions Once the tropical cyclone reaches winds of at least 39 mph (34 kt or 61 km/hr) they are typically called a tropical storm and assigned a name. If winds reach 74 mph (64 kt, 119 km/hr)), then they are called: As the storms get stronger, the Saffir-Simpson Scale is used. The Saffir-Simpson Scale is a 1-5 rating based on a hurricane's present intensity, used to give an estimate of the potential property damage and flooding expected along the coast from a hurricane landfall. Wind speed is the determining factor in the scale, as storm surge values are highly dependent on the slope of the continental shelf in the landfall region.

Note: All winds are using the U.S. 1-minute average. Sustained winds are defined as a 1-minute average wind measured at about 33ft (10m) above the surface.

Category 1

Winds 74 - 95 mph (64-82 knots or 119-153 km/hr)
Storm Surge Generally 4 - 5 ft above normal.
Estimated
Damage
No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Some damage to poorly constructed signs. Also, some coastal road flooding and minor pier damage.

Category 2

Winds 96 - 110 mph (83-95 knots or 154-177 km/hr)
Storm Surge Generally 6 - 8 ft above normal.
Estimated
Damage
Some roofing material, door, and window damage of buildings. Considerable damage to shrubbery and trees with some trees blown down. Considerable damage to mobile homes, poorly constructed signs, and piers. Coastal and low-lying escape routes flood 2-4 hours before arrival of the hurricane center. Small craft in unprotected anchorages break moorings.

Category 3

Winds 111 - 130 mph (96-113 knots or 178-209 km/hr)
Storm Surge Generally 9 - 12 ft above normal.
Estimated
Damage
Some structural damage to small residences and utility buildings with a minor amount of curtainwall failures. Damage to shrubbery and trees with foliage blown off trees and large tress blown down. Mobile homes and poorly constructed signs are destroyed. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the hurricane center. Flooding near the coast destroys smaller structures with larger structures damaged by battering of floating debris. Terrain continuously lower than 5 ft above mean sea level may be flooded inland 8 miles (13 km) or more. Evacuation of low-lying residences with several blocks of the shoreline may be required.

Category 4

Winds 131 - 155 mph (114-135 knots or 210-249 km/hr)
Storm Surge Generally 13 - 18 ft above normal.
Estimated
Damage
More extensive curtainwall failures with some complete roof structure failures on small residences. Shrubs, trees, and all signs are blown down. Complete destruction of mobile homes. Extensive damage to doors and windows. Low-lying escape routes may be cut by rising water 3-5 hours before arrival of the hurricane center. Major damage to lower floors of structures near the shore. Terrain lower than 10 ft above sea level may be flooded requiring massive evacuation of residential areas as far inland as 6 miles (10 km).

Category 5

Winds 155+ mph (135 knots or 249 km/hr)
Storm Surge Generally 18+ ft above normal.
Estimated
Damage
Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. All shrubs, trees, and signs blown down. Complete destruction of mobile homes. Severe and extensive window and door damage. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the hurricane center. Major damage to lower floors of all structures located less than 15 ft above sea level and within 500 yards of the shoreline. Massive evacuation of residential areas on low ground within 5-10 miles (8-16 km) of the shoreline may be required.
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