From June 1 through Nov. 30 each year, the Atlantic and Eastern Pacific oceans can become breeding grounds for some of the most destructive storms on the planet: hurricanes. These storms, which are broadly known as tropical cyclones, feed off warm ocean water. The ocean's rising heat turns into water vapor, which cools and condenses into rain. The heat released in the process helps strengthen circulating tropical cyclones, generating clusters of rain, thunder and strong winds.
Once winds reach 74 miles per hour (119 km/h), the storm is classified as a hurricane, and the Saffir-Simpson scale is used to measure its intensity. The scale starts with a Category 1, which ranges from 74 to 95 mph. Category 5 storms are the strongest with winds of 156 mph or greater, but storms of all sizes can and will cause a great deal of damage.
In 2005, Hurricane Katrina became one of the most devastating storms to hit U.S. soil. Fierce winds and surging ocean waters lashed the city of New Orleans, displacing millions of residents and killing more than 1,800 people, primarily in Louisiana and Mississippi.
Hurricane Sandy battered the East Coast of the United States in late October 2012. The storm, which spawned as a late-season post-tropical cyclone, flooded parts of New York, New Jersey, Maryland, Pennsylvania, West Virginia, Connecticut, Virginia and North Carolina. Nearly 300 people were killed (including deaths in Canada and the Caribbean), and the total cost of the storm has been estimated at $65 billion.