During 2018, 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 151 tropical cyclones had formed this year to date. 102 tropical cyclones were named by either a Regional Specialized Meteorological Center (RSMC) or a Tropical Cyclone Warning Center (TCWC).
With 151 tropical cyclones, 2018 was one of the most active years on record and was also regarded as the second-most intense tropical cyclone year on record, featuring eleven Category 5 tropical cyclones, according to the Saffir–Simpson Hurricane Wind Scale (SSHWS), only behind 1997. The most active basin in the year was the Western Pacific, which documented 28 named systems. The Eastern Pacific also saw an incredibly above-average year with 23 named systems, reaching the highest Accumulated Cyclone Energy (ACE) on record in the basin. Activity in the Atlantic Basin was unusually above average, with 15 tropical storms developing, despite the El Niño, which would usually suppress Atlantic activity. The North Indian Ocean was also above average, documenting seven named storms, making it the second-most active season in the basin's history since reliable records began. 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. The accumulated cyclone energy (ACE) index for 2018 (seven basins combined), as calculated by Colorado State University (CSU), was 1108.4 units, the second-highest since 1997.
The strongest tropical cyclone was Typhoon Mangkhut with a minimum pressure of 896 mbar/hPa (26.46 inHg), while the costliest tropical cyclone of the year was Hurricane Michael in the Atlantic, which struck Florida in October, causing US$25.1 billion in damage. The deadliest tropical cyclone of the year was Tropical Storm Son-Tinh in the West Pacific, which killed 170 people in Vietnam and Laos.
Global Atmospheric and Hydrological Conditions
In the Pacific Ocean, tropical cyclone activity was enhanced due to the above-average sea surface temperatures and the development of El Niño during the second half of the year. The eastern North Pacific experienced one of its active seasons on record, setting records for accumulated cyclone energy (ACE) and major hurricane days. Studies have also linked the basin's exceptional activity to warming in the subtropical North Pacific associated with the positive phase of the Pacific Meridional Mode.
In the North Atlantic Ocean, atmospheric and hydrological conditions were generally unfavorable for tropical cyclogenesis. In the tropical Atlantic, sea surface temperatures were cooler than average, characteristic of a negative phase of the Atlantic multidecadal oscillation (AMO). Additionally, high quantities of Saharan dust along with stronger-than-average upper-level wind shear over the tropical Atlantic created an unfavorable atmospheric environment.
Summary
North Atlantic Ocean
The 2018 Atlantic hurricane season was the third in a consecutive series of above-average and damaging Atlantic hurricane seasons, featuring fifteen named storms, eight hurricanes, and two major hurricanes, which caused a total of over $50 billion (2018 USD) in damages and at least 172 deaths.
The season began with the formation of Tropical Storm Alberto on May 25, marking the fourth consecutive year that activity began early. However, no storms developed in the month of June. July saw the formation of Beryl and Chris, both of which intensified into hurricanes. August also featured two named storms, Debby and Ernesto, though neither strengthened further than tropical storm status. On August 31, the depression that would later become Hurricane Florence developed. September featured the most activity, with Florence, Gordon, Helene, Isaac, Joyce, Tropical Depression Eleven, Kirk, and Leslie also forming or existing in the month. Florence, Helene, Isaac, and Joyce existed simultaneously for a few days in September, becoming the first time since 2008 that four named storms were active at the same time. The season also became the second consecutive year with three hurricanes simultaneously active.
Activity continued in October, with Michael forming on October 7 and strengthening into a major hurricane over the Gulf of Mexico before making landfall in the Florida Panhandle at peak intensity. Michael, which peaked as a Category 5 hurricane with maximum sustained winds of and a minimum barometric pressure of , was the most intense tropical cyclone of the season and one of only four storms to make landfall in the United States mainland as a Category 5, the others being the 1935 Labor Day hurricane, Hurricane Camille in 1969, and Hurricane Andrew in 1992. After 15 consecutive days as a tropical cyclone, Leslie transitioned into a powerful extratropical cyclone on October 13 while situated approximately west of the Iberian Peninsula, before making landfall soon afterward. A two-week period of inactivity ensued as the season began to wind down. Oscar, forming as a subtropical storm on October 26, intensified into a hurricane the next day, making it the eighth hurricane of the season. Oscar's extratropical transition ended the season's activity on October 31. No systems formed in the month of November for the first time since 2014.
The seasonal activity was reflected with an accumulated cyclone energy index value of 133 units. ACE is, broadly speaking, a measure of the power of a hurricane multiplied by the length of time it existed; therefore, long-lived storms and particularly strong systems result in high levels of ACE. The measure is calculated at full advisories for cyclones at tropical storm strength—storms with winds in excess of .
Eastern Pacific & Central Pacific Oceans
The 2018 Pacific hurricane season was one of the most active Pacific hurricane seasons on record, producing the highest accumulated cyclone energy value on record in the basin. The season had the fourth-highest number of named storms—23, tied with 1982. The season also featured eight landfalls, six of which occurred in Mexico. The season produced 26 tropical depressions formed, with 23 reaching tropical storm intensity. Thirteen of the tropical storms became hurricanes, with 10 reaching major hurricane intensity. The accumulated cyclone energy (ACE) index for the 2018 Pacific hurricane season was 316.565 units (201.9725 units for the Eastern Pacific and 114.5925 units for the Central Pacific).
The season started with the formation of Tropical Depression One-E on May 10, which was five days before the official start of hurricane season in the Eastern Pacific. The month of June saw record activity, with the formation of six tropical cyclonesAletta, Bud, Carlotta, Daniel, Emilia, and Seven-E. With five named systems, the record for most June tropical storms, which was set in 1985, was tied. Aletta and Bud both intensified into Category 4 major hurricanes, marking the first time since 2010 that two occurred in June. Tropical Storm Carlotta moved along the southern coast of Mexico, causing flooding rains. Activity during the month of July was below normal across the basin. Although a total of four tropical depressions formed, only two became stormsFabio and Gilma. Fabio's intensification into a tropical storm on July 1 marked the earliest date of a season's sixth named storm, beating the previous record of July 3 set in both 1984 and 1985.
August was an above-average month for the Eastern Pacific, with a total of seven named storms occurring during the monthHector, Ileana, John, Kristy, Lane, Miriam, and Norman. Forming from a July tropical depression, Hurricane Hector spent more days as a major hurricane than any other storm in the basin. It also had the highest accumulated cyclone energy since Hurricane John in 1994. Around the same time, Tropical Storm Ileana paralleled the southwestern coast of Mexico, bringing heavy rainfall to the region. Forming in mid-August, Hurricane Lane became the first Category 5 hurricane to form during the year. Lane brought record rainfall to Hawaii's Big Island, becoming the wettest tropical cyclone for that state and the second wettest in the United States. September saw the formation of five tropical cyclonesOlivia, Paul, Nineteen-E, Rosa, and Sergio. Hurricane Olivia became the first tropical cyclone in recorded history to make landfall on the islands of Maui and Lanai on September 12. Tropical Depression Nineteen-E formed in the Gulf of California on September 19, the first such instance in recorded history. It made landfall in Sonora on the next day, causing severe flooding. Additionally, one named storm formed in the Central Pacific in SeptemberWalaka. In October, Walaka intensified into a Category 5 hurricane in the Central Pacificthe season's second Category 5 storm.
October yielded an above-average number of tropical cyclones with three named storms formingTara, Vicente, and Willa. Sergio became the eighth system to obtain Category 4 intensity during the season, breaking the old record of seven which was set in 2015. Rosa and Sergio both made landfall on the Baja California Peninsula during October, bringing gale-force winds and rain to the region before impacting western Mexico. Willa became the season's third and last Category 5 hurricane before making landfall in Sinaloa, Mexico, in late October. The cyclone brought strong winds to the area where it made landfall and dropped torrential rainfall throughout the region. Tropical Storm Vicente caused severe flooding and landslides in western Mexico at the same time as Willa, compounding the latter's effects in some areas. November featured the season's last system, Tropical Storm Xavier, which dissipated on November 6, marking the end of the season.
Western Pacific Ocean
The 2018 Pacific typhoon season was the costliest Pacific typhoon season on record, until the record was beaten by the following year. The season was above-average, producing 29 storms, 13 typhoons, and 7 super typhoons.
The season began with Tropical Depression Agaton active to the east of the Philippines. Over the course of two days, the system moved over to the South China Sea and intensified into the first named storm, Bolaven. A month later, Tropical Storm Sanba developed and affected the southern Philippines. About another month later, Tropical Depression 03W formed in the open Pacific and was named Jelawat. Jelawat intensified into the season's first typhoon on March 30 and then the season's first super typhoon. Tropical activity fired up by June, when a series of storms developed, with Tropical Storm Ewiniar making landfall over mainland China. Later that month, Typhoon Prapiroon developed and affected the Korean Peninsula, the first since 2013. Thereafter, Typhoon Maria developed and reached its peak intensity as a Category 5 super typhoon, being the first typhoon to reach that intensity since Typhoon Nock-ten in 2016. Hurricane Hector crossed the International Date Line on August 13, the first to do so since Genevieve in 2014. Systems like Tropical Storms Son-tinh, Ampil, Josie, Wukong, Jongdari, Shanshan, Yagi, Leepi, Bebinca, and Rumbia formed between late July and early August.
On August 16, Typhoon Soulik developed and headed north until a Fujiwhara interaction with Typhoon Cimaron (which formed later than Soulik) made it head west towards the East China Sea. It later made landfall in South Korea, making it the first typhoon to make landfall in South Korea since Typhoon Chaba in 2016. Cimaron made landfall near Kyoto, Japan, on August 23. When Cimaron was nearing landfall, Tropical Depression Luis formed, which made landfall in China and Taiwan. Later that month, Typhoon Jebi developed over the West Pacific and intensified into the third super typhoon of the season.