Published: June 6,2017
Atlantic hurricane seasons since the satellite era began in the mid-1960s have had as many as 28 named storms and as few as four. Various factors in the atmosphere and the ocean typically drive whether a given hurricane season is busy or rather tame.
But ranking the most extreme hurricane seasons isn't as simple as examining the number of tropical storms and hurricanes that occurred in a given year. We need to dig a little deeper to capture the full picture.
A better way to rank the most extreme seasons is using the ACE (Accumulated Cyclone Energy) index which is calculated by adding each tropical storm or hurricane's wind speed through its life cycle.
Long-lived, intense hurricanes have a high ACE index, while short-lived, weak tropical storms have a low value. The ACE of a season is the sum of the ACE for each storm and takes into account the number, strength and duration of all the tropical storms and hurricanes in the season. A season's ACE value doesn't necessarily reflect the severity of impacts to land in a given season.
Below are the 10 most extreme hurricane seasons based on ACE index data from Colorado State University tropical scientist Dr. Phil Klotzbach. We've only included Atlantic hurricane seasons in the satellite era, which began in 1966, in order to have the most reliable information.
(MORE: Hurricane Central)
- ACE index: 149
- 11 named storms, 9 hurricanes, 2 major hurricanes (Category 3 or stronger)
- 62.25 named storm days, 38.25 hurricane days, 7.25 major hurricane days
All but two of the 11 named storms in the 1980 season became hurricanes.
Radar scan of Allen's eye from a NOAA P3 aircraft investigating the hurricane Aug. 7, 1980.
- ACE index: 165
- 19 named storms, 12 hurricanes, 5 major hurricanes
- 89.5 named storm days, 38.5 hurricane days, 11 major hurricane days
Igor was a major hurricane for nearly five days and was the strongest of the season, with maximum sustained winds of 155 mph at its peak. Bermuda and Atlantic Canada were both struck by Igor, and Newfoundland suffered its worst hurricane damage in recent history, the National Hurricane Center said.
Earl was a major hurricane for more than three days and grazed North Carolina's Outer Banks before making landfall in Nova Scotia as a Category 1.
Visible satellite image of Hurricane Igor on Sept. 14. 2010.
7. (tie) 1996
- ACE index: 166
- 13 named storms, 9 hurricanes, 6 major hurricanes
- 79 named storm days, 45 hurricane days, 13 major hurricane days
Edouard was a major hurricane for an exceptionally long time of nearly eight days, but that occurred well away from land in the open Atlantic Ocean.
North Carolina was struck by Hurricane Fran during the season; it was a Category 3 when it roared ashore near Cape Fear.
7. (tie) 1969
- ACE index: 166
- 18 named storms, 12 hurricanes, 5 major hurricanes
- 92.25 named storm days, 40.25 hurricane days, 6.5 major hurricane days
Another boost to the 1969 season's extreme nature was Inga, which spun through the Atlantic Ocean for nearly 25 days. It still holds the record as the third-longest-lived tropical cyclone in the Atlantic Basin.
(MORE: 10 Worst Hurricanes in American History)
A ship carried by Camille's storm surge rests alongside a home in Biloxi, Mississippi.
- ACE index: 176
- 16 named storms, 7 hurricanes, 3 major hurricanes
- 81.5 named storm days, 32.75 hurricane days, 16.75 major hurricane days
Isabel held its major hurricane status for nearly eight days, maxing out as a Category 5 for a total of 1.75 days during that time. Eastern parts of North Carolina and Virginia were pounded by Isabel, which made landfall as a Category 2.
Fabian is the other long-lived major hurricane of the 2003 season and curled through the Atlantic as a Category 3 or stronger for seven days. Bermuda saw extensive damage from Fabian, which passed very close to the archipelago as a Category 3.
Satellite image of Hurricane Isabel on Sept. 13, 2003 when it was strengthening back to Category 5 status. Several pinwheel-shaped features can be seen spinning inside the eye.
- ACE index: 177
- 12 named storms, 8 major hurricanes, 5 major hurricanes
- 78.5 named storm days, 41 hurricane days, 14.25 major hurricane days
All five of the major hurricanes in the 1999 season – Bret, Cindy, Floyd, Gert and Lenny – reached Category 4 strength.
Floyd first struck the Bahamas and then caused a deadly flood disaster in the eastern United States.
Lenny was an odd hurricane because it moved west-to-east in the Caribbean in November – the reverse direction of how storms usually track in that portion of the Atlantic Basin.
(MORE: Strange Places Hurricanes Have Formed Around the World)
- ACE index: 182
- 14 named storms, 10 hurricanes, 3 major hurricanes
- 88 named storm days, 48.5 hurricane days, 9.5 major hurricane days
Hurricane Mitch was the most powerful hurricane of 1998, maxing out at Category 5 strength off the coast of Honduras. Mitch was a flood and mudslide disaster for Central America that resulted in thousands of fatalities.
Bonnie and Georges are the two other hurricanes that had significant impacts in 1998.
Georges was a tropical cyclone for 17 days that moved from the Atlantic to the Caribbean and eventually the U.S. Gulf Coast, making seven landfalls along the way. The hurricane killed 602 people, mostly in the Dominican Republic and Haiti.
Bonnie was the third hurricane in a three-year span to directly impact North Carolina.
Flood damage along the Choluteca River caused by Hurricane Mitch in 1998 in Tegucigalpa, Honduras.
2. (tie) 1995
- ACE index: 227
- 19 named storms, 11 hurricanes, 5 major hurricanes
- 121.25 named storm days, 61.5 hurricane days, 11.5 major hurricanes
The most long-lived major hurricane of 1995 was Luis, which was Category 3 or stronger for eight consecutive days in early September and maxed out as a Category 4.
Opal reached Category 4 strength in the Gulf of Mexico in October and eventually made landfall as a Category 3 along the Florida Panhandle.
2. (tie) 2004
- ACE index: 227
- 15 named storms, 9 hurricanes, 6 major hurricanes
- 93 named storm days, 45.5 hurricane days, 22.25 major hurricane days
Chief among those was Hurricane Ivan, which is tied with Hurricane Allen (1980) for the longest total time as a Category 5 in the Atlantic at three days. Ivan left a trail of destruction from the Caribbean to the southeastern United States and was a major hurricane throughout that time.
Charley and Jeanne were both major hurricanes when they struck Florida in 2004. Frances was a major hurricane for more than six days in the Atlantic before it made landfall along Florida's eastern coast as a Category 2.
A zoomed in view of Hurricane Ivan's eye taken from the International Space Station as the powerful hurricane approached the Alabama and Florida Panhandle coasts on Sept. 15, 2004.
- ACE index: 250
- 28 named storms, 15 hurricanes, 7 major hurricanes
- 131.5 named storm days, 49.75 hurricane days, 17.5 major hurricane days
2005 also had the most major hurricanes in a season during the satellite era – seven. A record four hurricanes reached Category 5 status in the 2005 season, including Emily, Katrina, Rita and Wilma.
The incredible accolades of the 2005 season go on and on. See the link below for more details.
(RECAP: 2005 Hurricane Season by the Numbers)
The tracks of all 28 storms that occurred in the 2005 season. An unnamed subtropical storm was later added in post-season analysis, so only 27 of the storm were actually named.MORE: Atlantic Basin Retired Hurricanes and Tropical Storms
The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.