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 and the shape of the coastline, 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. Hurricane Lili
of 2002 made landfall on the Louisiana coast as a Category One hurricane.
Hurricane Gaston of 2004 was a Category One
hurricane that made landfall along the central South Carolina coast.
- 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 Frances of 2004 made landfall
over the southern end of Hutchinson Island, Florida as a Category Two hurricane.
Hurricane Isabel of 2003 made landfall near
Drum Inlet on the Outer Banks of North Carolina as a Category 2 hurricane.
- 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 trees 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 center of the hurricane.
Flooding near the coast
destroys smaller structures with larger structures damaged by
battering from 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
Ivan of 2004 were Category Three
hurricanes when they made landfall in Florida and in
- 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
center of the hurricane. 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 Charley of 2004 was
a Category Four hurricane made landfall in Charlotte County, Florida with winds of 150 mph.
Hurricane Dennis (pdf) of 2005 struck the island of Cuba as a Category Four hurricane.
- 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 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 center of
the hurricane. Major damage to lower floors of all structures
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. Only 3 Category
Five Hurricanes have made landfall in the United States
since records began: The Labor Day Hurricane of 1935, Hurricane
Camille (1969), and Hurricane Andrew
in August, 1992. The 1935 Labor Day Hurricane struck the Florida
Keys with a minimum pressure of 892 mb--the lowest pressure ever observed in
the United States. Hurricane Camille struck the Mississippi Gulf Coast
causing a 25-foot storm surge, which inundated Pass Christian.
Hurricane Katrina (pdf), a category 5 storm over the Gulf of Mexico,
was still responsible for at least 81 billion dollars of property damage when it struck the U.S. Gulf Coast as a
category 3. It is by far the costliest hurricane to ever strike the United States.
In addition, Hurricane Wilma (pdf) of 2005 was a
Category Five hurricane at peak intensity and is the strongest Atlantic
tropical cyclone on record with a minimum pressure of 882 mb.