A hurricane is a large, powerful storm that forms over warm ocean waters and can be up to 600 miles wide. Hurricanes are dangerous due to heavy rain, strong winds over 75 mph, and potential for flooding. Some key facts about hurricanes include that their waves can be as tall as houses, they have an eye in the center that is calm, and preparing for one involves putting up shutters and storm straps, evacuating if needed, and using sandbags.