Fast Facts on Hurricanes

The month of September is peak hurricane season.  The Atlantic Hurricane season is June 1st  through November 30th.  So as Florence makes her way slowly down the Atlantic coast, it seemed a good time to compile some fast facts on hurricanes.

A hurricane is a cyclonic tropical system that draws energy from the warm moist ocean air and expels energy up and out through cooler air clouds causing rain and thunderstorms that frequently generate tornadoes.

Tropical System Levels

• Tropical Depression —  sustained wind speeds of 38 mph or less
• Tropical Storm — sustained wind speeds of 39  to 73 mph
• Hurricane —  sustained wind speeds between 74 -160 mph.

The center “eye” generally has the calmest winds and can be 20-30 miles wide.

The “eyewall” is immediately surrounding the eye and generally has the strongest winds.  Most major hurricanes (category 3 or higher) with go through at least one eyewall replacement cycle where the eyewall collapses and reforms.

Hurricane vs Typhoon

“Hurricanes” are cyclones formed in Northern Hemisphere (Atlantic or eastern Pacific oceans) and spin counter-clockwise.   “Typhoons” are cyclones formed in the Southern Hemisphere and spin clockwise.

Wind vs Water

Hurricanes are frequently discussed in terms of their category on the Saffir-Simpson Hurricane Wind Scale, which is only determined by sustained wind speeds, while 90% of all hurricane deaths are due to storm surge.

• Storm Surge from a hurricane can be up to 20 feet high and 100 miles wide
• Rain produced from a hurricane can be more than 2.4 trillion gallons a day
• Wind damage by category on the Saffir-Simpson Hurricane Wind Scale:

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Check out the CDC’s report — Preparedness and safety messaging for hurricanes, flooding, and similar disasters.

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