The Saffir-Simpson Hurricane Wind Scale is a five-category rating based only on a hurricane’s maximum sustained wind speed, according to the National Hurricane Center. The center says the scale estimates potential property damage from wind. It does not take into account storm surge, rainfall flooding, or tornadoes.
What the scale measures
The National Hurricane Center describes the scale as a 1 to 5 rating based only on maximum sustained wind speed. The center says it is an estimate of potential property damage from wind. The scale is not a measure of total hurricane hazard.
The five categories and wind ranges
According to the National Hurricane Center, Category 1 hurricanes have sustained winds of 74 to 95 mph. Category 2 hurricanes have sustained winds of 96 to 110 mph. The center says Category 3, 4, and 5 hurricanes are major hurricanes, with Category 3 at 111 to 129 mph, Category 4 at 130 to 156 mph, and Category 5 at 157 mph or higher.
How the National Hurricane Center assigns categories
The National Weather Service states that the National Hurricane Center and Central Pacific Hurricane Center assign hurricane intensities in five-knot increments and convert them for advisories to miles per hour and kilometers per hour, rounded to the nearest five. To resolve rounding conflicts between units, the agency made a “minor modification” effective May 15, 2012. The change broadened Category 4 to 130 to 156 mph and adjusted Category 3 to 111 to 129 mph and Category 5 to 157 mph or higher, so a hurricane classified in knots would remain in the same category when shown in miles per hour or kilometers per hour.
What the categories imply for wind damage
The National Hurricane Center provides typical wind damage descriptions for each category. For Category 1, it says “Very dangerous winds will produce some damage,” including damage to roofs and siding, snapped large branches, toppled shallow-rooted trees, and power outages lasting a few to several days. For Category 2, it says “Extremely dangerous winds will cause extensive damage,” including major roof and siding damage to well-constructed frame homes, many snapped or uprooted shallow-rooted trees blocking roads, and near-total power loss that could last from several days to weeks.
For Category 3, the center says “Devastating damage will occur,” with well-built framed homes possibly having major roof decking and gable end damage, many snapped or uprooted trees blocking roads, and electricity and water unavailable for several days to weeks. For Category 4, it says “Catastrophic damage will occur,” with loss of most of the roof structure and some exterior walls in well-built homes, most trees snapped or uprooted, power poles downed, isolated residential areas, power outages for weeks to possibly months, and most of the area uninhabitable for weeks or months. For Category 5, it says “Catastrophic damage will occur,” with a high percentage of framed homes destroyed, total roof failure and wall collapse, isolated residential areas, power outages for weeks to possibly months, and most of the area uninhabitable for weeks or months.
What the scale does not include
The National Hurricane Center says the scale does not include other hazards such as storm surge, rain-induced floods, and tornadoes. The center notes that hurricanes of all categories can produce deadly storm surge, rainfall flooding, and tornadoes. It also states that these hazards call for protective actions, such as evacuating from areas vulnerable to storm surge.
Terms used in other regions
The National Hurricane Center notes that in the western North Pacific, the term “super typhoon” is used for tropical cyclones with sustained winds exceeding 150 mph.