Hurricanes occur 12 times a year in the Atlantic ocean, and on average cause billions of dollars in damage each time they strike. NOAA forecasters and scientists work to understand these massive storms that can cause dangerous flooding, high winds, and storm surges.
Hurricanes are the most intense tropical cyclones in the world and are classified as Category 3 or higher on the Saffir-Simpson scale. They have maximum sustained winds of 74 miles per hour or more, with gusts to 115 miles per hour in the center of the storm called an eye. They can last 2 weeks or more over open water and are a danger to ships at sea. They have been the cause of many shipwrecks including several in the Bermuda Triangle.
The force of a hurricane churns up the surface ocean, mixing warmer water near the surface with cooler nutrient-rich waters from deeper down in the water column in a process known as upwelling. This nutrient-rich water supports the growth of phytoplankton, which make food for other marine life. The churning also moves up nutrients from the sediments of coastal marshes and salt marshes, and from blue holes in the open ocean.
Hurricanes wreak havoc on coastal areas, but they also bring days of beneficial rainfall that helps replenish the very dry soil characteristic of southern summer and fall. This is good news for ecosystems because it allows animals to repopulate habitat that would otherwise be inaccessible during the summer and fall. It also reduces the buildup of toxic bacteria and red tide, which is worsened by very warm water associated with climate change.