Saffir-Simpson Hurricane Scale
Category 4
The Saffir-Simpson Hurricane Scale is a
Winds 131-155 mph (114-135 knots
1-5 rating based on the hurricane’s present
or 210-249 km/hr) ñ Storm surge gener-
intensity. This is used to give an estimate of
ally 13-18 ft above normal. More extensive
the potential property damage and flooding
curtainwall failures with some complete
expected along the coast from a hurricane
roof structure failures on small residences.
landfall. Herbert Saffir, a consulting engineer
Shrubs, trees, and all signs are blown down.
in Coral Gables, Florida, and Robert Simp-
Complete destruction of mobile homes.
son, who was then director of the National
Extensive damage to doors and windows.
Hurricane Center, developed the scale in the
Low-lying escape routes may be cut by rising
early 1970s. Wind speed is the determining
water 3-5 hours before arrival of the hurri-
factor in the scale, as storm surge values are
cane center. Major damage to lower floors of
highly dependent on the slope of the conti-
structures near the shore. Terrain lower than
nental shelf in the landfall region.
10 ft above sea level may be flooded, requir-
Category 1
ing massive evacuation of residential areas as
far inland as 6 miles (10 km).
Winds 74-95 mph (64-82 knots or 119-153
km/hr) ñ Storm surge generally 4-5 ft above
Category 5
normal. No real damage to building struc-
Winds greater than 155 mph (135 knots or
tures. Damage primarily to unanchored mo-
249 km/hr) ñ Storm surge generally greater
bile homes, shrubbery, and trees. Some dam-
than 18 ft above normal. Complete roof fail-
age to poorly constructed signs. Also, some
ure on many residences and industrial build-
coastal road flooding and minor pier damage.
ings. Some complete building failures, with
Category 2
small utility buildings blown over or away.
All shrubs, trees, and signs blown down.
Winds 96-110 mph (83-95 knots or
Complete destruction of mobile homes.
154-177 km/hr) ñ Storm surge generally
Severe and extensive window and door dam-
6-8 feet above normal. Some roofing mate-
age. Low-lying escape routes are cut by rising r
rial, door, and window damage of buildings.
water 3-5 hours before arrival of the hurri-
Considerable damage to shrubbery and trees,
cane center. Major damage to lower floors of
with some trees blown down. Considerable
all structures located less than 15 ft above sea
e
athe
damage to mobile homes, poorly construct-
level and within 500 yards of the shoreline.
W
ed signs, and piers. Coastal and low-lying
Massive evacuation of residential areas on
escape routes flood 2-4 hours before arrival
low ground within 5-10 miles (8-16 km) of
of the hurricane center. Small craft in unpro-
the shoreline may be required.
tected anchorages break moorings.
r
Depressions and Storms
Category 3
A Tropical Depression is a weather system
Winds 111-130 mph (96-113 knots or
with sustained winds greater than 35 mph.
e
athe
178-209 km/hr) ñ Storm surge generally
A Tropical Storm is a weather system with
9-12 ft above normal. Some structural dam-
sustained winds between 35 and 73 mph.
age to small residences and utility buildings
with a minor amount of curtainwall failures.
Currents
Damage to shrubbery and trees with foliage
There are more than 50 notable ocean cur-
blown off trees and large trees blown down.
rents moving water over the earth’s surface.
r
standing W
Mobile homes and poorly constructed signs
Major ocean currents can flow at rates of two
are destroyed. Low-lying escape routes are
knots or greater and persist over long peri-
nde
cut by rising water 3-5 hours before arrival
ods (months, years, or longer). The major U
of the hurricane center. Flooding near the
causes of ocean currents are prevailing winds
coast destroys smaller structures, with larger
and variations in the temperature and salin-
structures damaged by battering of floating
ity of the seawater. We often think of these
debris. Terrain continuously lower than 5 ft
currents as streams or rivers, flowing with
above mean sea level may be flooded inland
consistent direction and speed. In reality,
8 miles (13 km) or more. Evacuation of low-
ocean currents move at varying speeds and
lying residences with several blocks of the
in varying directions. Some actually reverse
shoreline may be required.
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