The National Hurricane Center classifies hurricanes according to their potential for producing extensive damages on a scale of 1 to 5. Herbert Saffir, a consulting engineer specializing in wind damage to buildings, and Robert Simpson, previous Director of the National Hurricane Center in the 1970s, invented the rating scale. The following table is a breakdown of the average wind, pressure and storm surge values for each of the five hurricane categories. The average atmospheric pressure is given in inches of mercury. The average sea-level atmospheric pressure is 29.92 inches of mercury. Wind speed is given in miles per hour (MPH). Generally speaking, Category 3 hurricanes and higher are categorized as major. Damages will increase exponentially as the category number is raised. (Refer to the table below.)

CATEGORY 1: Damage primarily to shrubbery, trees, and unanchored mobile homes. No real damage to other structures. Some damage to poorly constructed signs. Low-lying coastal roads inundated, minor pier damage, some small craft anchored in unprotected areas torn from moorings. 

CATEGORY 2: Considerable damage to shrubbery and tree foliage; some trees blown down. Major damage to exposed mobile homes. Extensive damage to poorly constructed signs; some damage to roofing materials of buildings; and some window and door damage. No major damage to buildings. Coastal roads and low-lying escape routes inland cut by rising water two to four hours before arrival of the hurricane's center. Considerable damage to piers. Marinas flooded and small craft anchored in unprotected areas torn from moorings.

CATEGORY 3: Foliage torn from trees; large trees blown down. Practically all poorly-constructed signs blown down; some damage to roofing materials of buildings; some window and door damage; and some structural damage to small buildings. Mobile homes destroyed. Serious flooding at coast and many smaller structures near coast destroyed; low-lying escape routes inland cut by rising water three to five hours before the hurricane's center arrives.

CATEGORY 4: Shrubs and trees blown down; all signs down. Extensive damage to roofing materials, windows and doors; complete failure of roofs on many small residences; complete destruction of mobile homes. Major damage to lower floors of structures near shore due to flooding and battering by waves and floating debris.

CATEGORY 5: Shrubs and trees blown down; considerable damage to roofs of buildings; all signs down; very severe and extensive damage to windows and doors; complete failure of roofs on many residences and industrial buildings; extensive shattering of glass in windows and doors; some complete building failures; small buildings overturned or blown away and complete destruction of mobile homes. Low-lying escape routes inland cut by rising water three to five hours before the hurricane's center arrives.