Hurricane Categories — The Saffir-Simpson Wind Scale

Hurricane categories classify tropical cyclones from Category 1 to Category 5 based strictly on maximum sustained wind speeds, delivering life-saving evaluations of structural damage, utility grid failure, and required evacuations.

The 1-to-5 Saffir-Simpson Classification & Damage Matrix

Official wind velocity boundaries and forensic damage appraisals based on National Hurricane Center operational standards.

Cat 1

Category 1

1-Min Sustained74–95 mph
Metric • Knots119–153 km/h (64–82 kt)

Very dangerous winds producing some damage

Structural ImpactVery dangerous winds will produce some damage: Well-constructed frame homes could have damage to roof, shingles, vinyl siding, and gutters.
Tree & Canopy DamageLarge branches of trees will snap and shallow rooted trees may be toppled.
Power Grid DowntimeExtensive damage to power lines and poles will result in outages that could last several days.
Cat 2

Category 2

1-Min Sustained96–110 mph
Metric • Knots154–177 km/h (83–95 kt)

Extremely dangerous winds with extensive damage

Structural ImpactExtremely dangerous winds will cause extensive damage: Substantial roof and siding damage to frame homes; major mobile home destruction.
Tree & Canopy DamageMany shallowly rooted trees will be snapped or uprooted and block numerous roads.
Power Grid DowntimeNear-total power loss is expected with outages that could last from several days to a couple of weeks.
Cat 3

Category 3

1-Min Sustained111–129 mph
Metric • Knots178–208 km/h (96–112 kt)

Devastating damage expected — major hurricane

Structural ImpactDevastating damage will occur: Well-built frame homes may incur major damage or removal of roof decking and gable ends.
Tree & Canopy DamageMany trees will be snapped or uprooted, blocking numerous roads and isolating neighborhoods.
Power Grid DowntimeElectricity and water will be unavailable for several days to weeks after the storm passes.
Cat 4

Category 4

1-Min Sustained130–156 mph
Metric • Knots209–251 km/h (113–136 kt)

Catastrophic damage — power outages for weeks

Structural ImpactCatastrophic damage will occur: Well-built homes can sustain severe damage with loss of most of the roof structure and some exterior walls.
Tree & Canopy DamageMost trees will be snapped or uprooted and power poles downed, isolating residential areas.
Power Grid DowntimePower outages will last for weeks to possibly months. Long-term water shortages are likely.
Cat 5

Category 5

1-Min Sustained157+ mph
Metric • Knots252+ km/h (137+ kt)

Catastrophic damage — uninhabitable areas for weeks or months

Structural ImpactCatastrophic damage: A high percentage of framed homes will be completely destroyed, with total roof failure and wall collapse.
Tree & Canopy DamageNearly all trees will be completely snapped, uprooted, or defoliated; wooden utility poles obliterated.
Power Grid DowntimeTotal power and communications failure lasting for months. Area will be largely uninhabitable.
TD

Tropical Depression

1-Min Sustained< 39 mph
Metric • Knots< 63 km/h (< 34 kt)

Minimal threat with disorganized storms

Structural ImpactVirtually no structural damage to well-built homes or mobile properties.
Tree & Canopy DamageMinimal foliage disturbance; occasional weak tree limb snaps.
Power Grid DowntimeIsolated, short-term power disruptions primarily from falling branches.
TS

Tropical Storm

1-Min Sustained39–73 mph
Metric • Knots63–118 km/h (34–63 kt)

Dangerous winds and flooding possible

Structural ImpactMinor damage to shingles, siding, and unanchored outdoor equipment.
Tree & Canopy DamageBranches broken off trees; shallowly rooted small trees may be toppled.
Power Grid DowntimeScattered power outages lasting several hours to a couple of days.

Critical Hazards Not Measured by the Saffir-Simpson Scale

Why relying solely on the wind category can create dangerous false senses of security.

Coastal Storm Surge Inundation

Storm surge accounts for nearly 50% of direct tropical cyclone fatalities. Surge height is governed by underwater continental shelf slope and storm size, NOT wind speed alone. A broad Category 2 storm can produce a far more catastrophic surge than a compact Category 4.

Torrential Freshwater Rainfall

A hurricane's total rainfall accumulation is dictated primarily by its forward translation speed, not its wind intensity. Slow-moving or stalling storms (such as Hurricane Harvey in 2017) can dump over 50 inches of rain regardless of whether they are a Category 1 or Category 4.

Physical Wind Field Radius

The Saffir-Simpson Scale measures the peak wind speed at a single point near the eyewall. It conveys nothing about whether hurricane-force winds extend 20 miles outward or 150 miles outward, profoundly altering the geographic scope of destruction.

The History & Formulation of the Scale

How a civil engineer and a hurricane director revolutionized emergency public communication in 1971.

Herbert Saffir & Dr. Robert Simpson (1971)

In 1969, civil engineer Herbert Saffir prepared a United Nations study on low-cost housing wind resistance. Realizing there was no simple scale akin to the Richter scale for earthquakes, he developed a 1-to-5 index based on structural shear forces.

Dr. Robert Simpson, then Director of the National Hurricane Center, integrated barometric pressure and storm surge estimates, establishing the official operational Saffir-Simpson Hurricane Scale in 1971.

The 2010 NOAA Operational Revision

Following Hurricane Ike (2008)—where a Category 2 wind produced a lethal 20-foot Category 4-scale storm surge—the National Weather Service formally decoupled storm surge and pressure ranges from the scale in 2010.

Today, the tool is officially designated the Saffir-Simpson Hurricane Wind Scale, communicating purely aerodynamic wind hazards, while standalone high-resolution SLOSH storm surge inundation maps warn coastal zones.

Frequently Asked Questions About Hurricane Categories

Track Active Storm Categories on the Live Map

Examine active tropical systems and check real-time NOAA sustained winds, category badges, and projected paths.