The Saffir-Simpson Hurricane Scale
The Saffir-Simpson Hurricane Scale is a 1-5 rating based on the
hurricane's present intensity. This is 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 that all winds are using the U.S. 1-minute
average.
- Category One Hurricane:
- Winds 74-95 mph (64-82 kt or 119-153 km/hr). Storm surge generally 4-5
ft above normal. 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.
Hurricanes Allison of
1995 and Danny of 1997
were Category One hurricanes at peak intensity.
- Category Two Hurricane:
- Winds 96-110 mph (83-95 kt or 154-177 km/hr). Storm surge generally 6-8
feet above normal. 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.
Hurricane Bonnie of
1998 was a Category Two hurricane when it hit the North Carolina coast,
while Hurricane Georges
of 1998 was a Category Two Hurricane when it hit the Florida Keys and the
Mississippi Gulf Coast.
- Category Three Hurricane:
- Winds 111-130 mph (96-113 kt or 178-209 km/hr). Storm surge generally
9-12 ft above normal. 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. Hurricanes
Roxanne of 1995 and Fran
of 1996 were Category Three hurricanes at landfall on the Yucatan Peninsula
of Mexico and in North Carolina, respectively.
- Category Four Hurricane:
- Winds 131-155 mph (114-135 kt or 210-249 km/hr). Storm surge generally
13-18 ft above normal. 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).
Hurricane Luis of 1995 was a Category Four hurricane while moving over
the Leeward Islands. Hurricanes
Felix and
Opal of 1995 also
reached Category Four status at peak intensity.
- Category Five Hurricane:
- Winds greater than 155 mph (135 kt or 249 km/hr). Storm surge generally
greater than 18 ft above normal. 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 destructon 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.
Hurricane Mitch of 1998
was a Category Five hurricane at peak intensity over the western Caribbean.
Hurricane Gilbert of
1988 was a Category Five hurricane at peak intensity and is the strongest
Atlantic tropical cyclone of record.