# Hurricane Damage Potential

The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 categorization based on the hurricane's intensity at the indicated time. The maximum sustained surface wind speed (peak 1-minute wind at 33 feet/10 meters) is the determining factor in the scale.

This scale provides examples of the type of damages and impacts in the United States associated with winds of the indicated intensity. In general, it shows damages rise by about a factor of four for every category increase.

However, this does not address the potential for such other hurricane-related impacts, such as storm surge, rainfall-induced floods, and tornadoes. When these additional factors are considered the rate of increase in damage is much higher.

When asked to rate potential damage from a category one hurricane to a category two or three storm most people's results are often linear in increasing damage.

However, since the potential damage increase from category to category is logarithmic then small increases in wind strength can dramatically increase damage.

When the cost from hurricane related damages are normalized (normalization takes into account inflation, changes in population, and changes in wealth to arrive at a common level for comparison) the result shows an eighth-power increase1 in damages from category to category.

What this means is the potential damage from a hurricane is 28 power. For example, a doubling of the wind speed from 75 mph (121 km/h) to 150 mph (241 km/h) is not a doubling or quadrupling of potential damage but a 256 times increase (2 x 2 x 2 x 2 x 2 x 2 x 2 x 2=256).

This is evident in that over 85% of all damages from hurricanes come from category three, four, and five storms, yet these storms make up only 24% of all landfalling storms2.

This table shows the rate of increase for various wind speeds in a hurricane as compared to a minimal 75 mph (121 km/h) category one hurricane. These values indicate the multiple increase in damage potential ABOVE damage that occurs with a 75 mph hurricane.

Catagory Wind Speed Damage
Potential
Multiplier
mph km/h knots
1 75 121 65 1x
80 129 70 1.6x
85 137 74 2.9x
90 145 78 4.3x
95 153 83 6.6x
2 100 161 87 10x
105 169 91 15x
110 177 96 21x
3 115 185 100 30x
120 193 104 43x
125 201 109 60x
4 130 209 113 82x
135 217 117 110x
140 225 122 147x
145 233 126 195x
150 241 130 256x
155 249 135 333x
5 160 257 139 429x
165 266 143 549x
170 274 148 697x
175 281 152 879x
180 290 156 1101x
185 298 161 1371x
190 306 165 1696x

Remember, damage WILL occur with a 75 mph (121 km/h) hurricane. The multiplier values are the potential damage increases above what could occur with a 75 mph (121 km/h) storm. Note the rapid increase in potential damage just within each category. A 95 mph hurricane can produce nearly seven times the damage as a 75 mph (121 km/h) hurricane with just a 20 mph (32 km/h) increase in wind strength.

A 10 mph (16 km/h) increase in wind speed, from 100 mph (161 km/h) to 110 mph (177 km/h), results in over doubling potential damage from 10-times that of a 75 mph (121 km/h) hurricane to 21-times.

What does this mean for you? Do not be lulled into complacency if you hear of a small increase in wind speed from a hurricane. These small increases directly lead to increasingly greater damage potential. Be wise and make preparations in advance to evacuate should law enforcement officers order evacuations.

Hurricane damage potential from: (1) Nordhaus, William D. "The Economics of Hurricanes in the United States" National Bureau of Economic Research (December 2006) and (2) R. A. Pielke, Jr. and colleagues. "Normalized Hurricane Damage in the United States: 1900-2005" Natural Hazard Review (2008)