Hurricane Category Definitions
Hurricane Preparedness Week starts the first week of May. Here’s information from the National Hurricane Center at the National Weather Service (NWS) and other sources about how hurricane categories are defined and what can of damage they can do.
Both hurricanes and typhoons are tropical cyclones—a generic term used by meteorologists to describe a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has closed, low-level circulation.
Cyclones occur in the Southern Pacific Ocean andthe Indian Ocean, with those that occur in northwest Pacific with wind speeds that reach or exceed 74 mph are “typhoons.” In the western North Pacific, the term “super typhoon” is used for tropical cyclones with sustained winds exceeding 150 mph.
Hurricanes are found near the tropical zone, over warm waters in the Atlantic and Pacific oceans. (For more details, visit Cyclone vs. Hurricane.)
The NWS uses the Saffir-Simpson Hurricane Scale to determine the category (based on wind speed) and the potential property damage and flooding along the coast that can occur from a hurricane landfall.
- Sustained winds of 74-95 mph (64-82 kt) (119-153 km/h)
- Types of damage: Very dangerous winds will produce some damage, with well-built frame homes having damage to roofs, shingles, vinyl shutters and gutters. Large branches can snap and shallowly rooted trees may topple. Power lines and poles can sustain damage leading to power outages.
- Sustained winds of 96-110 mph (83-95 kt) (154-177 km/h)
- Types of damage: Extremely dangerous winds will cause extensive damage, with well-built frame homes potentially sustaining major roof and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is expected with outages that could last from several days to weeks.
Category 3 (major)
- Sustained winds of 111-129 mph (96-112 kt) (178-208 km/h)
- Types of damage: Devastating damage will occur, with well-built frame homes possibly incurring major damage or removal of roof decking and gable ends. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes.
Category 4 (major)
- Sustained winds of 130-156 mph (113-136 kt) (209-251 km/h)
- Types of damage: Catastrophic damage will occur, with well-built frame homes possibly sustaining severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.
Category 5 (major)
- Sustained winds of 157 mph or higher (137 kt or higher) (252 km/h or higher)
- Types of damage: Catastrophic damage will occur, with a high percentage of well-built frame homes destroyed, with total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months.