Tropical cyclones are ranked on one of five tropical cyclone intensity scales, according to their maximum sustained winds and which tropical cyclone basins they are located in. Only a few classifications are used officially by the meteorological agencies monitoring the tropical cyclones, but other scales also exist, such as accumulated cyclone energy, the Power Dissipation Index, the Integrated Kinetic Energy Index, and the Hurricane Severity Index.
Traditionally, areas of tropical cyclone formation are divided into seven basins. These include the North Atlantic Ocean, the eastern and western parts of the North Pacific Ocean, the Southwest Pacific, the Southwest and Southeast Indian Oceans, and the North Indian Ocean. The West Pacific is the most active and the north Indian the least active. An average of 86 tropical cyclones of tropical storm intensity form annually worldwide, with 47 reaching hurricane/typhoon strength, and 20 becoming intense tropical cyclones, super typhoons, or major hurricanes.
In the south-west Indian Ocean, tropical cyclones form south of the equator and west of 90° E to the coast of Africa.
The following outline is provided as an overview of and topical guide to tropical cyclones:
2010, with only 64 named systems, was considered as one of the least active years for tropical cyclones on record. During the year, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, a total of 111 tropical cyclones developed, with 64 of them being named by either a Regional Specialized Meteorological Center (RSMC) or a Tropical Cyclone Warning Center (TCWC). The most active basin was the North Atlantic, which documented 19 named systems, while the North Indian Ocean, despite only amounting to five named systems, was its basin's most active since 1998. Conversely, both the West Pacific typhoon and East Pacific hurricane seasons experienced the fewest cyclones reaching tropical storm intensity in recorded history, numbering 14 and 8, respectively. Activity across the southern hemisphere's three basins—South-West Indian, Australian, and South Pacific—was spread evenly, with each region recording 7 named storms apiece. The southern hemisphere's strongest tropical cyclone was Cyclone Edzani, which bottomed out with a barometric pressure of 910 mbar in the South-West Indian Ocean. Nineteen Category 3 tropical cyclones formed, including four Category 5 tropical cyclones in the year. The accumulated cyclone energy (ACE) index for the 2010, as calculated by Colorado State University was 573.8 units.
During 2005, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, a total of 141 systems formed with 94 of these developing further and were named by the responsible warning centre. The strongest tropical cyclone of the year was Hurricane Wilma, which was estimated to have a minimum barometric pressure of 882 hPa (26.05 inHg). 2005 was above-average in terms of the number of storms. The most active basin in the year was the North Atlantic, which documented 28 named systems. The Western Pacific had an near-average season with 23 named storms. The Eastern Pacific hurricane season experienced an above-average number of tropical storm intensity systems, numbering 15. Activity across the southern hemisphere's three basins – South-West Indian, Australian, and South Pacific – was fairly significant, with the regions recording 23 named storms altogether, with the most intense Southern Hemisphere cyclone of the year, Cyclone Percy from the South Pacific Ocean basin peaking at 145 mph (235 km/h) and 900 millibars. Throughout the year, 28 Category 3 tropical cyclones formed, including eight Category 5 tropical cyclones in the year. The accumulated cyclone energy (ACE) index for the 2005, as calculated by Colorado State University was 899.6 units.
Throughout 2006, 133 tropical cyclones formed in seven bodies of water known as tropical cyclone basins. Of these, 80 have been named, including two tropical cyclones in the South Atlantic Ocean, and a tropical cyclone in the Mediterranean Sea, by various weather agencies when they attained maximum sustained winds of 65 km/h (40 mph). The strongest storms of the year were Typhoon Yagi in the Western Pacific, and Cyclone Glenda of the Australian region. The deadliest and costliest storms of the year were a series of five typhoons that struck the Philippines and China; Chanchu, Bilis, Saomai, Xangsane, and Durian, with most of the damage being caused by Durian of November. So far, 27 Category 3 tropical cyclones formed, including five Category 5 tropical cyclones in the year. The accumulated cyclone energy (ACE) index for the 2006, as calculated by Colorado State University was 761 units.
During 2007, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, a total of 129 systems formed with 79 of these developing further and were named by the responsible warning centre. The strongest tropical cyclone of the year was Cyclone George, which was estimated to have a minimum barometric pressure of 902 hPa (26.64 inHg). The deadliest tropical cyclone of the year was Cyclone Sidr in the North Indian Ocean which killed 15,000 people in Bangladesh. The costliest tropical cyclone of the year was Cyclone Gonu in the North Indian Ocean, which caused more than $4.41 billion in damage after striking Oman, United Arab Emirates, Iran and Pakistan. The most active basin in the year was the Western Pacific, which documented 24 named systems. The North Atlantic had an above-average season with 15 named storms. The Eastern Pacific hurricane season experienced a below-average number of tropical storm intensity systems, numbering 11. Activity across the Southern Hemisphere's three basins – South-West Indian, Australian, and South Pacific – was fairly significant, with the regions recording 25 named storms altogether, with the most intense storm of the year coming from the Australian basin. Throughout 2007, twenty one major tropical cyclones formed, including five Category 5 tropical cyclones in the year. The accumulated cyclone energy (ACE) index for the 2007, as calculated by Colorado State University was 568.1 units.
The 2013–14 South-West Indian Ocean cyclone season was an above-average event in tropical cyclone formation. The season officially began on July 1, 2013, though the first tropical system designated by Météo-France was a short-lived tropical disturbance that developed on July 8. However, the first named storm was Cyclone Amara in December. Bruce was the first very intense tropical cyclone since Edzani in 2010, which originated from the Australian region. The strongest system of the cyclone season was Hellen, also one of the most intense tropical cyclones over the Mozambique Channel. The season officially ended on June 30, 2014
Intense Tropical Cyclone Amara was a very strong tropical cyclone which brought stormy conditions to Rodrigues in December 2013. Amara was the first named storm in the southwest Indian Ocean during the later half of 2013, and developed from a disturbance within the monsoon trough on December 15. The following day, the system attained tropical depression status. Despite its ill-defined organization, the depression was able to continue strengthening, reaching moderate tropical storm status on December 16 as it tracked southwest. Situated in a favorable atmospheric environment, a period of rapid intensification ensued after Amara reached tropical cyclone status on December 18. After fluctuating in strength, the cyclone peaked with maximum sustained winds of 205 km/h (125 mph) and a minimum barometric pressure of 935 mbar on December 21, making it an intense tropical cyclone based on the intensity scale utilized by Météo-France. Shortly after, wind shear increased as Amara tracked southeast, resulting in a weakening phase. The shearing effects caused the cyclone to rapidly decay, and by December 23, Amara degenerated into a remnant low.
The 2016–17 South-West Indian Ocean cyclone season was a below-average season, with five tropical storms, three of which intensified into tropical cyclones. It officially began on November 15, 2016, and ended on April 30, 2017, with the exception for Mauritius and the Seychelles, for which it ended on May 15, 2017. These dates conventionally delimit the period of each year when most tropical and subtropical cyclones form in the basin, which is west of 90°E and south of the Equator. Tropical and subtropical cyclones in this basin were monitored by the Regional Specialised Meteorological Centre in Réunion, though the Joint Typhoon Warning Center issued unofficial advisories.
During 2015, tropical cyclones formed in seven major bodies of water, commonly known as tropical cyclone basins. Tropical cyclones will be assigned names by various weather agencies if they attain maximum sustained winds of 35 knots. During the year, one hundred thirty-four systems have formed and ninety-two were named. The most intense storm of the year was Hurricane Patricia, with maximum 1-minute sustained wind speeds of 345 km/h (215 mph) and a minimum pressure of 872 hPa (25.75 inHg). The deadliest tropical cyclone was Cyclone Komen, which caused 280 fatalities in Southeast India and Bangladesh, while the costliest was Typhoon Mujigae, which caused an estimated $4.25 billion USD in damage after striking China. Forty Category 3 tropical cyclones formed, including nine Category 5 tropical cyclones in the year. The accumulated cyclone energy (ACE) index for the 2015, as calculated by Colorado State University (CSU) was 1047 units.
During 2004, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, a total of 132 systems formed with 82 of these developing further and were named by the responsible warning centre. The strongest tropical cyclone of the year was Cyclone Gafilo, which was estimated to have a minimum barometric pressure of 895 hPa (26.43 inHg). The most active basin in the year was the Western Pacific, which documented 29 named systems, while the North Atlantic 15 named systems formed. Conversely, both the Eastern Pacific hurricane and North Indian Ocean cyclone seasons experienced a below average number of named systems, numbering 12 and 4, respectively. Activity across the southern hemisphere's three basins—South-West Indian, Australian, and South Pacific—was spread evenly, with each region recording seven named storms apiece. Throughout the year, 28 Category 3 tropical cyclones formed, including seven Category 5 tropical cyclones formed in the year. The accumulated cyclone energy (ACE) index for the 2004, as calculated by Colorado State University was 1024.4 units.
During 2012, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, a total of 128 tropical cyclones had formed this year to date. 85 tropical cyclones had been named by either a Regional Specialized Meteorological Center (RSMC) or a Tropical Cyclone Warning Center (TCWC).
Throughout 2013, 139 tropical cyclones formed in seven different areas called basins. Of these, 67 have been named by various weather agencies when they attained maximum sustained winds of 35 knots. The strongest and deadliest tropical cyclone of the year was Typhoon Haiyan, which was estimated to have a minimum barometric pressure of 895 hPa (26.43 inHg) and caused at least 6,300 deaths in the Philippines. The costliest tropical cyclone of the year was Hurricane Manuel, which was responsible for at least $4.2 billion worth of damages in Mexico. 21 major tropical cyclones formed in 2013, including five Category 5 tropical cyclones. The accumulated cyclone energy (ACE) index for the 2013, as calculated by Colorado State University was 618.5 units.
During 2011, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, a total of 131 tropical cyclones had formed this year to date. 71 tropical cyclones had been named by either a Regional Specialized Meteorological Center (RSMC) or a Tropical Cyclone Warning Center (TCWC). Thirty-nine of these named systems eventually intensified into hurricane-equivalent tropical cyclones. The most active basin in the year was the Western Pacific, which documented 21 named storms. North Atlantic basin documented 19 named storms, continuing the consecutive third-most active season trends from the previous year, due to the 2010–12 La Niña event. Conversely, the Eastern Pacific basin featured slightly more activity than the previous season, with 11 named storms. The least active basin in the year was the North Indian Ocean basin which documented only 2 named storms, the lowest since the 1993 season. Activity across the Southern Hemisphere were almost evenly spread, with the South-West Indian Ocean basin recording 10 tropical cyclones, the Australian region recording 17 tropical cyclones, and the South Pacific basin also recording 10 tropical cyclones, respectively. Twenty-one Category 3 tropical cyclones formed in the year, including three Category 5 tropical cyclones. The accumulated cyclone energy (ACE) index for the 2011, as calculated by Colorado State University was 573.8 units.
During 2001, tropical cyclones formed in seven different areas called basins, located within various parts of the Atlantic, Pacific and Indian Oceans. A total of 128 tropical cyclones formed within bodies of water known as tropical cyclone basins, with 83 of them were further named by the responsible weather agencies when they attained maximum sustained winds of 35 knots. Typhoon Faxai is the strongest tropical cyclone throughout the year, peaking with a pressure of 915 hPa (27.02 inHg) and attaining 10-minute sustained winds of 195 km/h (120 mph). The deadliest tropical cyclone of the year was Lingling in the West Pacific which caused 379 fatalities in total as it struck the Philippines and Vietnam, while the costliest storm of the year was Michelle, with a damage cost of around $2.43 billion as it catastrophically affected the Greater Antilles and the Bahamas in late October. So far, 23 Category 3 tropical cyclones formed, including two Category 5 tropical cyclones formed in the year. The accumulated cyclone energy (ACE) index for the 2001, as calculated by Colorado State University was 672.4 units.
During 2000, tropical cyclones formed in seven different areas called basins, located within various parts of the Atlantic, Pacific, and Indian Oceans. A total of 140 tropical cyclones formed within bodies of water known as tropical cyclone basins, with 81 of them being further named by their responsible weather agencies when they attained maximum sustained winds of 35 knots. The strongest storm of the year was Cyclone Hudah, peaking with a minimum pressure of 905 hPa (26.72 inHg), and with 10-minute sustained winds of 220 km/h (135 mph). The highest confirmed number of deaths from a storm was from Typhoon Kai-tak, which killed 188 people, however, Leon–Eline may have killed up to 722 people. The costliest storm was Saomai, which caused $6.3 billion in damage. The accumulated cyclone energy (ACE) index for the year 2000, as calculated by Colorado State University was 677.3 units.
During 1996, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific, and Indian Oceans. During the year, a total of 139 tropical cyclones formed in bodies of water known as tropical cyclone basins. 90 of them were named by various weather agencies when they attained maximum sustained winds of 35 knots. The strongest tropical cyclone of the year was Cyclone Daniella, peaking with a pressure of 915 hPa (27.02 inHg) in the open waters of the Indian Ocean. Hurricane Fran and Typhoon Herb tie for the costliest storm of the year, both with a damage cost of $5 billion. The deadliest tropical cyclone of the year was the 1996 Andhra Pradesh cyclone, which was blamed for over 1,000 fatalities as it directly affected the state of Andhra Pradesh in India. Five Category 5 tropical cyclones were formed in 1996. The accumulated cyclone energy (ACE) index for the 1996, as calculated by Colorado State University was 960 units.
During 1991, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, a total of 100 systems formed with 75 of these developing further and were named by the responsible warning centre. The strongest tropical cyclone of the year was Typhoon Yuri, which was estimated to have a minimum barometric pressure of 895 hPa (26.43 inHg). The deadliest tropical cyclone was Cyclone BOB 01, which caused 138,866 fatalities in Bangladesh, Northeastern India, Myanmar, Yunnan, while the costliest was Typhoon Mireille, which caused an estimated $10 billion USD in damage after striking Japan. Four Category 5 tropical cyclones formed in 1991.
