As nature unleashes Hurricane Irma on the Carribean and likely Florida, it is time to consider just how damaging a major hurricane can be.  The United States has gone years before Hurricanes Harvey and Irma without a major hurricane making landfall.  We are overdue.

If Hurricane Irma impacts the United States at category 4 or 5 strength, the effects will be devastating.

As hurricane winds increase, the force of the wind does not increase linearly, but exponentially.  A category 5 storm is not five times more destructive than a category 1 storm.  It is 500 times more destructive!

With luck Hurricane Irma will weaken and head offshore.  If it stays strong and close — watch out and prepare!

The Saffir-Simpson Hurricane Wind Scale

Category Wind (km/h) Wind (mph) Description
1 119-153 74-95 Very dangerous winds will produce some damage. Flying or falling debris could injure or kill people and animals. Older mobile homes could be destroyed. Newer mobile and frame-construction homes, apartment buildings and shopping centers can sustain exterior damage (i.e. roof, siding, gutters). Flying debris can break windows in high-rise buildings- falling and broken glass will pose a significant danger. Some damage to commercial signage and fences will occur, large tree branches will snap and shallow- rooted trees can be toppled. Extensive damage to power lines and poles will likely result in power outages that will last a few to several days.
2 154-177 96-110 Extremely dangerous winds will cause extensive damage. There is a substantial risk of injury or death to people and animals due to flying and falling debris. Older mobile homes have a high chance of being destroyed and flying debris generated can shred nearby homes. Newer mobile and frame-construction homes, apartment buildings and shopping centers can sustain major exterior damage (i.e. roof, siding, gutters). Flying debris can break windows in high-rise buildings- falling and broken glass will pose a significant danger. Commercial signage and fences will be damaged if not destroyed, shallow- rooted trees will be snapped or uprooted and block roads. Near-total power loss is expected with outages that could last from several days to weeks, and potable water could become scarce.
3 178-209 111-130 Devastating damage will occur. There is a high risk of injury or death to people and animals due to flying and falling debris. Older mobile homes will be destroyed and most newer mobile homes will sustain severe damage, including potential roof failure and wall collapse. There will be a high percentage of roof covering and siding damage to well-built frame-construction homes, apartment buildings and shopping centers. Isolated structural damage to wood or steel framing can occur. Numerous windows will be blown out of high-rise buildings- falling and broken glass will pose a significant danger. Commercial signage and fences will be destroyed, many trees will be snapped or uprooted and block roads. Electricity and water will be unavailable for several days to a few weeks after the storm.
4 4210-249 131-155 Catastrophic damage will occur. Large amounts of windborne debris will be lofted into the air. There is a high risk of injury or death to people and animals due to flying and falling debris. Older mobile homes and a high percentage of newer mobile homes will be destroyed. Well-built homes can also sustain severe damage with significant losses to roof structures and/or some exterior walls. Extensive damage to roof coverings, windows, and doors will occur. Top floors of apartment buildings will sustain structural damage, steel frames in older industrial buildings and older unreinforced masonry buildings can collapse. Most windows will be blown out of high-rise buildings- falling and broken glass will pose a significant danger. Commercial signage and fences will be destroyed, most trees will be snapped or uprooted and power poles down. Power outages will last for weeks to possibly months, long-term water shortages can be expected, and most of the area will be uninhabitable for weeks or months.
5 249+ 155+ Catastrophic damage will occur. Large amounts of windborne debris will be lofted into the air. There is a very high risk of injury or death to people and animals due to flying and falling debris. Almost all mobile homes will be destroyed. A high percentage of frame homes will be destroyed, with total roof failure and wall collapse. A high percentage of industrial buildings and low-rise apartment buildings will be destroyed. Complete collapse of older metal buildings can occur and most unreinforced masonry walls will fail which can lead to building collapse. Nearly all windows will be blown out of high-rise buildings- falling and broken glass will pose a significant danger. Nearly all commercial signage and fences will be destroyed, almost all trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months, long-term water shortages can be expected, and most of the area will be uninhabitable for weeks or months.