During 2016, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, 135 tropical cyclones formed in bodies of water known as tropical cyclone basins. Of these, 83, including two subtropical cyclones in the South Atlantic Ocean and two tropical-like cyclones in the Mediterranean, were named by various weather agencies when they attained maximum sustained winds of . The strongest storm of the year was Winston, peaking with a pressure of and with 10-minute sustained winds of before striking Fiji. The costliest and deadliest tropical cyclone in 2016 was Hurricane Matthew, which impacted Haiti, Cuba, Florida, Georgia and the Carolinas, causing $16.5 billion in damage. Matthew killed 603 people; 546 in Haiti, 47 in United States, 4 in Cuba and Dominican Republic, and 1 in Colombia and St. Vincent.
2016 had a slightly above average amount of tropical cyclones forming in the year. The most active basin of the year was the Western Pacific documenting a record 26 named storms. The Eastern Pacific also had an above-average season with 21 named storms forming. The North Atlantic similarly was the first above-average since 2012 with 15 named storms and 7 hurricanes forming. The above activity can be blamed on a La Niña pattern which formed during the summer of the year. In the North Indian Ocean was a relatively below-average season which featured four named storms. The Southern Hemisphere had relatively average activity throughout much of the year– with the exception of the Australian region which remained below average because of positive IOD– the other South-West Indian Ocean and South Pacific basins featured above-average seasons. Eight Category 5 tropical cyclones were formed in 2016. The accumulated cyclone energy (ACE) index for the 2016 (seven basins combined), as calculated by Colorado State University (CSU) was 806.5 units.
Tropical cyclones are primarily monitored by a group of ten warning centers, which have been designated as a Regional Specialized Meteorological Centre (RSMC) or a Tropical Cyclone Warning Center (TCWC) by the World Meteorological Organization. These are the United States National Hurricane Center (NHC) and Central Pacific Hurricane Center, the Japan Meteorological Agency (JMA), the Indian Meteorological Department (IMD), Météo-France (MFR), Indonesia's Badan Meteorologi, Klimatologi, dan Geofisika, the Australian Bureau of Meteorology (BOM), Papua New Guinea's National Weather Service, the Fiji Meteorological Service (FMS) as well as New Zealand's MetService. Other notable warning centers include the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), the United States Joint Typhoon Warning Center (JTWC), and the Brazilian Navy Hydrographic Center(BNHC).
Global atmospheric and hydrological conditions
During November and December 2015, values within NOAA's Oceanic Niño Index peaked at , which surpassed December 1997 value of . NOAA subsequently reported that the 3-month average from November 2015 to January 2016 of the ONI had peaked at , which meant that the 2014–16 event was tied with the 1997–98 event for the strongest values on record. However, overall the event was considered to be one of the three strongest El Nino events since 1950, since there was a number of different ways to measure the strength of an event. The event subsequently started to weaken with sea surface temperature anomalies across the equatorial pacific decreasing, while predictions about a possible La Niña event taking place during 2016 started to be made.
During May 2016, the El Niño event dissipated as near to below average sea surface temperatures, expanded across the eastern equatorial Pacific Ocean. Atmospheric anomalies over the tropical Pacific Ocean had also weakened and become consistent with ENSO neutral conditions. These anomalies included the traditional and equatorial Southern Oscillation indices becoming near zero, while atmospheric convection, upper and lower level winds all became near average. As a result of this the BoM, NOAA's CPC, IRI, and the JMA, all declared that the record-tying El Niño event had ended in late May/early June.
Summary
North Atlantic Ocean
The 2016 Atlantic hurricane season officially began on June 1, 2016. It was an above average season and the most active since 2012, producing a total of 15 named storms, 7 hurricanes, and 4 major hurricanes. The first storm, Hurricane Alex, developed on January 12, while the final system, Hurricane Otto, made a crossover to the Eastern Pacific on November 25. The higher-than-normal activity was attributed to many factors. Most significantly, one of the strongest El Niño events recorded in history rapidly dissipated, transforming to cool-neutral conditions across the Pacific in late summer. This led to warmer than normal sea surface temperatures across the Atlantic, though the subtropical regions were slightly cooler than normal; slightly lower than normal sea level pressures; and reduced wind shear, especially in the Caribbean, which had experienced record values of wind shear in the past recent years. Moisture levels, however, were anomalously dry, which likely prevented some of the storms from becoming significant hurricanes. Steering currents had also been different from past years, which had previously had a trough of low pressure dominating the East Coast of the United States. The tropical cyclones of this season caused about $16.1 billion in damage and at least 748 deaths,
being the costliest season since 2012, the deadliest since 2008. The Atlantic hurricane season officially ended on November 30, 2016. The season's activity was reflected with an accumulated cyclone energy index of 141 units, which was well above the 1981–2010 median of 92, as well as the highest value since 2010.
The year opened up with an anomalous storm in January: Hurricane Alex, the first such system to develop in January since 1938. Activity picked up at the end of May into June, with three consecutive tropical storms: Bonnie, Colin, and Danielle. The latter two were the earliest third- and fourth-named storms on record. July saw no storm development for the first time in four years, however. August saw the formation of five tropical cyclones, including Earl, Fiona, Gaston, Eight, and Hermine. A Category 1 hurricane, Earl wrought tremendous damage in Belize and Mexico. With 81 lives lost in Mexico during the passage of Earl, it was the deadliest Atlantic hurricane in the country since 2005. Gaston became the season's first major hurricane on August 28, attaining peak winds of over the central Atlantic. On September 1, Hermine struck the Florida Peninsula as a Category 1 hurricane, ending an 11-year drought of hurricane landfalls in the state, which began after Hurricane Wilma in October 2005.
September featured another five tropical cyclones: Ian, Julia, Karl, Lisa, and Matthew, the latter of which persisted into October. Matthew proved to be the most significant storm of the season, becoming the first Category 5 hurricane in the Atlantic since Hurricane Felix in 2007, and, with a death toll of over 600, it was the deadliest in the Atlantic basin since Hurricane Stan in 2005. It subsequently struck Haiti as a Category 4 hurricane, and inflicted catastrophic damage across the impoverished nation. Matthew also caused extensive damage in Cuba, the Bahamas, and the Southeastern United States. Concurrently, Hurricane Nicole meandered south of Bermuda for more than a week before making a direct hit on the territory as a major hurricane. The next four weeks were quiet, until Hurricane Otto formed in the southwestern Caribbean during late November. Otto eventually became the latest-forming major hurricane in the Atlantic basin on record, surpassing a storm in 1934. After striking Nicaragua and becoming the first hurricane on record to pass over Costa Rica, Otto – the final tropical cyclone of the season – then emerged into the Eastern Pacific basin on November 25, the first such occurrence since Hurricane Cesar–Douglas in 1996.
Eastern & Central Pacific Oceans
The season was tied as the fifth-most active season on record, alongside the 2014 season. Throughout the course of the year, a total of 22 named storms, 13 hurricanes and six major hurricanes were observed within the basin. Although the season was very active, it was considerably less active than the previous season, with large gaps of inactivity at the beginning and towards the end of the season. It officially started on May 15 in the eastern Pacific, and on June 1 in the central Pacific; they both ended on November 30. As illustrated by Hurricane Pali, which became the earliest Central Pacific tropical cyclone on record, the formation of tropical cyclones is possible at any time of the year. Although Pali formed in January, the season kicked off to a very inactive start; for the first time since 2011, no tropical depressions or storms formed during the month of May, and no named storms formed during June since 2007.
Agatha formed on July 2, the latest first named storm in the eastern Pacific proper since 1969. Despite this, the season set a record for the most number of storms during the first half of July. When Georgette formed on July 21, it became the seventh named storm to form in the month of July; equaling the previous record set in 1985 and 2015 for the most active July since reliable records began. And when Frank became a hurricane (after Georgette did so), it marked a record-high 5 hurricanes in July. Finally, Howard formed on July 31, however, was not named until August 1, one named storm shy of the record. Despite that, the season tied the record set in 1985 with the most named storms in July. Activity in August was slightly less active than July. Lester and Madeline threatened the Big Island at hurricane strength. Lester passed north of the islands, Madeline brought some rain as the storm dissipated south of Hawaii. Javier and Newton followed similar paths close to the Mexican coast, with both making landfall in the Baja California Peninsula in August and early September respectively. After Newton led off September; Hurricanes Orlene, Paine and Tropical Storm Roslyn followed forming far from land. Hurricane Ulika became the first tropical cyclone on record to cross 140°W three times; it also became the first named storm in the Central Pacific basin since Pali back in January. Ulika was the first storm since Ela in 2015 to form in the Eastern Pacific, but not be named until entering the Central Pacific. After an unusually quiet October, Hurricane Seymour became the sixth major hurricane of the season, as well as the strongest. Tropical Storm Tina formed close to the coast of Mexico in mid-November. In late November, Tropical Storm Otto entered the basin from the Atlantic, becoming the eighteenth tropical cyclone to do so; however, it dissipated quickly due to unfavorable conditions.
Western Pacific Ocean