Saffir–Simpson scale in the context of "Hurricane Katrina"

Climate change affects tropical cyclones in a variety of ways: an intensification of rainfall and wind speed, an increase in the frequency of very intense storms and a poleward extension of where the cyclones reach maximum intensity are among the consequences of human-induced climate change. Tropical cyclones use warm, moist air as their source of energy or fuel. As climate change is warming ocean temperatures, there is potentially more of this fuel available.

Between 1979 and 2017, there was a global increase in the proportion of tropical cyclones of Category 3 and higher on the Saffir–Simpson scale. The trend was most clear in the north Indian Ocean, North Atlantic and in the Southern Indian Ocean. In the north Indian Ocean, particularly the Arabian Sea, the frequency, duration, and intensity of cyclones have increased significantly. There has been a 52% increase in the number of cyclones in the Arabian Sea, while the number of very severe cyclones have increased by 150%, during 1982–2019. Meanwhile, the total duration of cyclones in the Arabian Sea has increased by 80% while that of very severe cyclones has increased by 260%. In the North Pacific, tropical cyclones have been moving poleward into colder waters and there was no increase in intensity over this period. With 2 °C (3.6 °F) warming, a greater percentage (+13%) of tropical cyclones are expected to reach Category 4 and 5 strength. A 2019 study indicates that climate change has been driving the observed trend of rapid intensification of tropical cyclones in the Atlantic basin. Rapidly intensifying cyclones are hard to forecast and therefore pose additional risk to coastal communities.

The 2005 Atlantic hurricane season was a record-breaking, devastating and deadly Atlantic hurricane season. It is the second-costliest hurricane season, just behind the 2017 season. It featured 28 tropical and subtropical storms, which was the most recorded in a hurricane season until the 2020 season. The United States National Hurricane Center named 27 storms, exhausting the annual pre-designated list, requiring the use of six Greek letter names, and adding an additional unnamed subtropical storm during a post-season re-analysis. A record 15 storms attained hurricane status, with maximum sustained winds of at least 74 miles per hour (119 km/h). Of those, a record seven became major hurricanes, rated Category 3 or higher on the Saffir–Simpson scale. Four storms of this season became Category 5 hurricanes, the most of any season on record.

The four Category 5 hurricanes during the season were: Emily, Katrina, Rita, and Wilma. In July, Emily reached peak intensity in the Caribbean Sea, becoming the first Category 5 hurricane of the season, later weakening and striking Mexico twice. It was the first Category 5 hurricane recorded in the month of July and was the earliest-forming Category 5 hurricane on record, until Hurricane Beryl surpassed the record in July 2024. In August, Katrina reached peak winds in the Gulf of Mexico but weakened by the time it struck the U.S. states of Louisiana and Mississippi. The most devastating effects of the season were felt on the Gulf Coast of the United States, where Katrina's storm surge crippled New Orleans, Louisiana, for weeks and devastated the Mississippi coastline. Katrina became the costliest U.S. hurricane, leaving $125 billion in damage and 1,392 deaths. Rita followed in September, reaching peak intensity in the Gulf of Mexico before weakening and hitting near the border of Texas and Louisiana. The season's strongest hurricane, Wilma, became the most intense Atlantic hurricane on record, as measured by barometric pressure. Lasting for ten days in October, Wilma moved over Cozumel, the Yucatán Peninsula, and Florida, causing over $22 billion in damage and 52 deaths.

Hurricane Hugo was a powerful tropical cyclone that inflicted widespread destruction across the northeastern Caribbean and the Southeastern United States in September 1989. The eleventh tropical cyclone, eighth named storm, sixth hurricane, and second major hurricane of the 1989 Atlantic hurricane season, Hugo arose from a cluster of thunderstorms near Cape Verde on September 10, 1989. This cluster coalesced into a tropical depression and strengthened into Tropical Storm Hugo as it tracked west across the Atlantic Ocean for several days. On September 13, Hugo became a hurricane and continued to intensify through September 15 when its sustained winds peaked at 160 mph (255 km/h), making it a Category 5 hurricane on the Saffir–Simpson scale. Between September 17 and 21, Hugo made landfall on Guadeloupe, Saint Croix, Puerto Rico, and lastly South Carolina, with major hurricane strength winds. The storm weakened inland and accelerated north over the Eastern United States, transitioning into an extratropical cyclone on September 23 before it was last noted in the far northern Atlantic on September 25.

Hugo left extensive damage in its wake, causing 61 deaths and $11 billion (equivalent to $28 billion in 2024) in damage, which at the time, made it the costliest tropical cyclone on record worldwide. Guadeloupe bore the brunt of the storm in the Leeward Islands. Three thousand houses were unroofed, contributing to the displacement of 35,000 people from their homes. Hugo was Montserrat's costliest hurricane on record and brought down the island's entire power grid. Ninety percent of homes on the island suffered significant to total roof loss after the island was struck by the eyewall. The hurricane's impacts continued into the Virgin Islands and Puerto Rico, causing over $1 billion in damage. Wind gusts up to 168 mph (270 km/h) were measured in Saint Croix, where property damage exceeded $500 million with over 90 percent of buildings damaged; three people were killed on the island. Widespread damage occurred in Puerto Rico and much of the island suffered power and water service failures. Eight people were killed in Puerto Rico and nearly 28,000 people were left homeless. In the mainland United States, coastal South Carolina was hit by record setting storm surge heights, reaching 20.2 ft (6.2 m) near McClellanville. The surge and strong winds wrought extensive damage to buildings and infrastructure across South Carolina, and caused 13 deaths. Flood and wind impacts followed Hugo across much of the Eastern United States into Eastern Canada.

Hurricane Florence was a powerful and long-lived tropical cyclone that caused catastrophic damage in the Carolinas in September 2018, primarily as a result of freshwater flooding due to torrential rain. The sixth named storm, third hurricane, and the first major hurricane of the 2018 Atlantic hurricane season, Florence originated from a strong tropical wave that emerged off the west coast of Africa on August 30, 2018. The wave steadily organized, and strengthened into a tropical depression on the next day near Cape Verde. Progressing along a steady west-northwest trajectory, the system gradually strengthened, acquiring tropical storm strength on September 1. An unexpected bout of rapid intensification ensued on September 4–5, culminating with Florence becoming a Category 4 major hurricane on the Saffir–Simpson scale (SSHWS), with estimated maximum sustained winds of 130 mph (215 km/h). Strong wind shear then led to rapid weakening, and Florence weakened to tropical storm strength on September 7. Shifting steering currents led to a westward turn into a more suitable environment; as a result, Florence reintensified to hurricane strength on September 9 and major hurricane status by the following day. Florence reached peak intensity on September 11, with 1-minute winds of 150 mph (240 km/h) and a minimum central pressure of 937 mbar (27.7 inHg). An unexpected eyewall replacement cycle and decreasing oceanic heat content caused a steady weakening trend; however, the storm grew in size at the same time. Early on September 14, Florence made landfall in the United States just south of Wrightsville Beach, North Carolina as a Category 1 hurricane, and weakened further as it slowly moved inland under the influence of weak steering currents. Florence degenerated into a post-tropical cyclone over West Virginia on September 17 and was absorbed by another frontal storm two days later.

Early in the storm's history, the system brought squalls to the Cape Verde islands, resulting in minor landslides and flooding; however, overall effects remained negligible. With the threat of a major impact in the Southeastern and Mid-Atlantic United States becoming evident by September 7, the governors of North Carolina, South Carolina, Virginia, Georgia, and Maryland, and the mayor of Washington, D.C. declared a state of emergency. On September 10 and 11, the states of North Carolina, South Carolina, and Virginia issued mandatory evacuation orders for some of their coastal communities, predicting that emergency personnel would be unable to reach people there once the storm arrived. Though Florence made landfall as a greatly weakened Category 1 hurricane, winds associated with the tropical cyclone were strong enough to uproot trees and power lines, causing extensive power outages across the Carolinas. Furthermore, due to the slow motion of the storm, heavy rain fell throughout the Carolinas for several days. Coupled with a powerful storm surge, the rainfall caused widespread flooding along a long stretch of the North Carolina coast, from New Bern to Wilmington. Inland flooding from Florence inundated cities such as Fayetteville, Smithfield, Lumberton, Durham, and Chapel Hill. Most major roads and highways in the area experienced flooding, with large stretches of I-40, I-95, and US Route 70 remaining impassable for days after the storm's passage. Wilmington was cut off entirely from the rest of the mainland by the flooding. The storm also spawned tornadoes in several places along its path, including an EF2 tornado that killed one person in Virginia. Many places received record-breaking rainfall, with Florence setting maximum rainfall records from a tropical cyclone in both of the Carolinas. Overall, the storm caused $24.23 billion in damage, mostly in the Carolinas, and 54 deaths.

Within the North Atlantic Ocean, a Category 3 hurricane is a tropical cyclone, that has 1-minute sustained wind speeds of between 96–112 knots (110–129 mph; 178–207 km/h; 49–58 m/s). Since the beginning of the Atlantic hurricane database in 1851, 162 tropical cyclones peaked at Category 3 strength on the Saffir–Simpson scale in the Atlantic basin, which covers the waters of the Atlantic Ocean north of the equator, the Caribbean Sea, and the Gulf of Mexico. This list does not include hurricanes that intensified further to a Category 4 or 5, the latter being the highest ranking on the scale.

Collectively, Category 3 Atlantic hurricanes caused nearly $100 billion in damage. Most of the damage total was caused by Hurricane Sandy in 2012, which left $68.7 billion in damage when it struck New Jersey as a post-tropical cyclone, and which was briefly a major hurricane near Cuba.

Hurricane Irma was an extremely powerful and devastating tropical cyclone that caused extensive damage and loss of life across the Antilles and Eastern United States in September 2017. Irma was the first Category 5 hurricane to strike the Leeward Islands on record, though it was followed by Hurricane Maria, which struck the region at Category 5 intensity as well two weeks later. At the time, Irma was considered the most powerful hurricane on record in the open Atlantic region, outside of the Caribbean Sea and Gulf of Mexico, until it was surpassed by Hurricane Dorian two years later. It was also the third-strongest Atlantic hurricane at landfall ever recorded, just behind the 1935 Labor Day hurricane, Hurricane Melissa, and Dorian.

The ninth named storm, fourth hurricane, second major hurricane, and first Category 5 hurricane of the extremely active 2017 Atlantic hurricane season, Irma developed from a tropical wave near the Cape Verde Islands on August 30. Favorable conditions allowed Irma to rapidly intensify into a Category 3 hurricane on the Saffir–Simpson wind scale by late on August 31. The storm's intensity fluctuated between Categories 2 and 3 for the next several days, due to a series of eyewall replacement cycles. On September 4, Irma resumed intensifying, becoming a Category 5 hurricane by early on the next day. Early on September 6, Irma peaked with 1-minute sustained winds of 180 mph (290 km/h) and a minimum pressure of 914 hPa (27.0 inHg). Irma was the second-most intense tropical cyclone worldwide in 2017 in terms of barometric pressure, and the strongest worldwide in 2017 in terms of wind speed. Another eyewall replacement cycle caused Irma to weaken back to a Category 4 hurricane, but the storm re-attained Category 5 status before making landfall in Cuba. Although Irma briefly weakened to a Category 2 storm while making landfall on Cuba, the system re-intensified to Category 4 status as it crossed the warm waters of the Straits of Florida, before making landfall on Cudjoe Key on September 10. Irma then weakened to Category 3 status, prior to another landfall in Florida on Marco Island later that day. The system degraded into a remnant low over Alabama and ultimately dissipated on September 13 over Missouri.

In meteorology, an eyewall replacement cycle, also called a concentric eyewall cycle, is a process whereby some of the outer rainbands of a tropical cyclone with an eye strengthen and organize into a ring of thunderstorms—a new, outer eyewall—that slowly moves inward and robs the original, inner eyewall of its needed moisture and angular momentum. Since the strongest winds are in a tropical cyclone's eyewall, the storm usually weakens during this phase, as the inner wall is "choked" by the outer wall. Eventually the outer eyewall replaces the inner one completely, and the storm may re-intensify.

They naturally occur in intense tropical cyclones with maximum sustained winds greater than 33 m/s (64 kn; 119 km/h; 74 mph), or hurricane-force, and particularly in major hurricanes of Saffir–Simpson category 3 to 5.

Hurricane Mitch was a powerful, extremely deadly and catastrophic tropical cyclone in 1998 that became the second-deadliest Atlantic hurricane on record. Mitch caused 11,374 fatalities in Central America, including approximately 7,000 in Honduras and 3,800 in Nicaragua due to cataclysmic flooding from the slow motion of the storm. It was the deadliest hurricane in Central American history, surpassing Hurricane Fifi–Orlene, which killed slightly fewer people in the same area in 1974. Mitch was the deadliest Atlantic hurricane in the satellite era, and the second-deadliest on record in the Atlantic, only behind the Great Hurricane of 1780 which killed at least 22,000 people.

The thirteenth named storm, ninth hurricane, and third major hurricane of the 1998 Atlantic hurricane season, Mitch formed in the western Caribbean Sea on October 22, and after responding to extremely favorable conditions, it rapidly strengthened to peak at Category 5 status, the highest possible rating on the Saffir–Simpson scale. After drifting southwestward and weakening, the hurricane hit Honduras as a minimal Category 1 hurricane. Mitch roved through Central America, regenerated in the Bay of Campeche, and ultimately impacted Florida as a strong tropical storm. It then became extratropical and accelerated northeastward across the North Atlantic, before dissipating on November 9. At the time, Mitch was the strongest Atlantic hurricane observed in the month of October, surpassing Hurricane Hattie of the 1961 season. The record would stand for seven years until it would be broken by Hurricane Wilma of the 2005 season. In addition, Mitch is the tenth-most intense Atlantic hurricane on record, tied with Hurricane Dean in 2007 in terms of pressure.