Typhoons and hurricanes are measured using different scales. The Saffir-Simpson scale is used for hurricanes and is as follows.

The scale used for typhoons is different and was developed by the Japanese Meteorological Agency, The China Meteorological Administration and the Hong Kong Observatory. That scale follows.

There are other scales used in the Indian Ocean, South-Western Indian Ocean, and waters surrounding Australia and Fiji. The scales are relatively similar across territories with minor variations.

 Category 1

In general the stronger the hurricane the more damage that is caused, but that is not always the case. A weaker hurricane may cause more damage in a populated area than a stronger hurricane causes in a less populated, open area. The more construction there is, the more likely there will be damage.

With a category 1 hurricane the storm surge is around four to five feet. Storm surge is an increase in the ocean's level, and can be in excess of several feet. It is often the most damaging feature of a hurricane, especially when it occurs during high tide in low-lying areas. Storm surge is often responsible for most hurricane deaths; people cannot escape the rising water. A category 1 hurricane causes some damage to trees and shrubbery and unanchored mobile homes. Hurricane Katrina in 2005 was at different times a category 1 hurricane and a category 3. It caused severe flooding due to the low-lying areas it inundated. Hurricane Agnes in 1972 was category 1. Agnes caused $11 billion in damages.

 Category 2

Category 2 hurricanes have storm surge between six and eight feet. A category 2 hurricane will cause major damage to mobile homes, damage buildings' roofs, and blow trees down. Blowing trees will cause damage to property as they fall onto houses or get blown through windows. Coastal roads/low escape routes will be flooded two to four hours before the storm. Two feet of water can float most cars, even SUVs. Six inches of rapidly moving water can knock a person off his feet. Roofs, windows, and doors may be damaged. Hurricane David in 1979 was a category 2 hurricane and caused $320 million in damage.

 Category 3

Category 3 hurricanes have storm surge of nine to twelve feet, destroys mobile homes, downs large trees, and damages small buildings. The standard ceiling height is eight feet. Suspended ceilings are generally seven and a half feet, while tall ceilings are nine to ten feet. Signs will be down, and structural damage will occur to small buildings and homes. Serious flooding may occur at the coast, and waves and debris will damage large and destroy small structures. Roads will be cut off three to five hours before the storm hits and flat terrain less than five feet above sea level will be flooded inland eight miles or more. Local evacuations will be in force. Piers and marinas will be damaged and flooded. Evacuations of low-lying island and shoreline residents may be put in force. Hurricanes Ivan and Jeanne in 2004, and Katrina, Wilma and Dennis in 2005 were category 3 hurricanes. Jeanne caused $8 billion, Wilma $20 billion, Ivan $19 billion and Dennis $25 billion in damages. Katrina was the costliest hurricane on record at $105 billion.

 Category 4

Category 4 hurricanes have storm surges of thirteen to eighteen feet, completely destroy mobile homes, and lower floors of structures near the shore are susceptible to flooding. Trees and all signs will be down, structural damage will be severe with complete failure of some roofs. Flat terrain less than ten feet above sea level will be flooded six miles inland. There will be major beach erosion, all residences within 500 yards and single-story homes on low ground within two miles will be evacuated. Roads will be cut off three to five hours before the storm. A storm surge going through a beach house can easily fill the first floor with water. Hurricane Charley in 2004 was a category 4 hurricane, as was Hurricane Hugo in 1989 and Hazel in 1954. Charley caused $15 billion and Hugo 9 billion in damages.

 Category 5

Category 5 hurricanes are the strongest, and only one is on record: Hurricane Andrew in 1992, which caused $45 billion in damage. The storm surge will be eighteen feet or higher. A category 5 hurricane will cause extensive damage to homes and industrial buildings, blow away small buildings, and significantly damage lower floors of structures within 500 meters of shore and less than fifteen feet above sea level. Major erosion will occur, evacuation will take place within five to ten miles of the shore. Roads again will be cut off three to five hours before the storm, and major damage to lower floors of all structures less than fifteen feet above sea level and within 500 yards of shore will take place.

Summary

Hurricanes are very damaging and deadly; unfortunately, there are often many deaths with hurricanes. Hurricane Melissa has devastated Jamaica, with peak sustained winds of 185 mph. Damages will be extensive.
 A list of the most costly hurricanes can be found here. 

Many people underestimate the strength and power of hurricanes and do not realize the amount of damage even a small storm can cause. Another factor is how well the buildings and grounds are maintained. Trees with dead limbs break apart easily and can damage nearby structures, and older roofs are more susceptible to having shingles blown off and other damage. However, even the most well-built, well-maintained building is going to be damaged in a category 5 hurricane.