2005 - The answer: most active season in history
The question: what is the 2005 Atlantic hurricane season. Several records were broken that year including most storms in a season (28), most storms that became hurricanes (15), and most catagory 5 hurricanes (4). The most remembered is Hurricane Katrina that hit the Louisiana and Mississippi coasts and whose storm surge caused massive flooding in New Orleans.
NOAA Hurricane Page http://hurricanes.noaa.gov/
National Hurricane Center http://www.nhc.noaa.gov/