Hurricanes start out as a region of thunderstorms called easterly waves and grow into tropical depressions, then to tropical storms and if conditions are extremely favorable to development, to hurricanes. Our hurricane season starts June 1 and ends November 30 each year.
Hurricanes are classified according to the Saffir-Simpson scale shown below. One should note that the power of wind increases as the cube of the wind speed so that a doubling of wind speed causes an 8-fold increase in wind power! Therefore, a category 5 hurricane's wind is at least 8 times more powerful than a minimal category 1 hurricane.
Strength |
Wind Speed (mph) |
Pressure (millibars) |
Pressure (inches Hg) |
Storm Surge (ft) |
|---|---|---|---|---|
|
Category 1 |
74 - 95 |
>980 |
>28.94 |
4 - 5 |
|
Category 2 |
96 - 110 |
965 - 979 |
28.50 - 28.91 |
6 - 8 |
|
Category 3 |
111 - 130 |
945 - 964 |
27.91 - 28.47 |
9 - 12 |
|
Category 4 |
131 - 155 |
920 - 944 |
27.17 - 27.88 |
13 - 18 |
|
Category 5 |
>155 |
<919 |
<27.16 |
>18 |
|
Tropical Depression |
23 - 39 mph |
|
Tropical Storm |
40 - 73 mph |
|
Hurricane |
74+ mph |
For more information about Hurricanes, what causes them, etc, please visit The National Hurricane Survival Initiative.
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Hurricanes start out as a region of thunderstorms called easterly waves and grow into tropical depressions, then to tropical storms and if conditions are extremely favorable to development, to hurricanes. Our hurricane season starts June 1 and ends November 30 each year.
Hurricanes are classified according to the Saffir-Simpson scale shown below. One should note that the power of wind increases as the cube of the wind speed so that a doubling of wind speed causes an 8-fold increase in wind power! Therefore, a category 5 hurricane's wind is at least 8 times more powerful than a minimal category 1 hurricane.
Strength |
Wind Speed (mph) |
Pressure (millibars) |
Pressure (inches Hg) |
Storm Surge (ft) |
|---|---|---|---|---|
|
Category 1 |
74 - 95 |
>980 |
>28.94 |
4 - 5 |
|
Category 2 |
96 - 110 |
965 - 979 |
28.50 - 28.91 |
6 - 8 |
|
Category 3 |
111 - 130 |
945 - 964 |
27.91 - 28.47 |
9 - 12 |
|
Category 4 |
131 - 155 |
920 - 944 |
27.17 - 27.88 |
13 - 18 |
|
Category 5 |
>155 |
<919 |
<27.16 |
>18 |
|
Tropical Depression |
23 - 39 mph |
|
Tropical Storm |
40 - 73 mph |
|
Hurricane |
74+ mph |
For more information about Hurricanes, what causes them, etc, please visit The National Hurricane Survival Initiative.
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