Hurricane Irma
What was the wind speed of Hurricane Irma?
How long did Hurricane Irma maintain its category 5 status?
What was the estimated damage cost and death toll from Hurricane Irma?
Hurricane Irma, one of the longest-lasting category 5 hurricanes on record that hit the Caribbean and the southern United States in 2017. With sustained wind speeds of 185 miles (298 km) per hour, Irma was the strongest tropical cyclone to strike the Caribbean at the time of landfall and the strongest hurricane recorded over the open Atlantic Ocean as of 2025. Between August 30 and September 12, Irma made landfall seven times across the Caribbean and Florida, causing widespread destruction. The effects of Irma were so great that the World Meteorological Organization retired the name in 2017.
Four of Irma’s landfalls were at category 5 strength, with wind speeds of more than 157 miles (253 km) per hour. It spent a total of 78 hours as a category 5 storm, tying the 1932 Cuba Hurricane of Santa Cruz del Sur for the longest duration in that category on record. Irma maintained its top wind speed of 185 miles (298 km) per hour for 37 hours, longer than any other tropical cyclone in history. At its most intense, Irma’s barometric pressure dropped to 914 millibars, an almost 10 percent decrease, creating an atmospheric vacuum. Irma’s core at its peak was relatively compact, with hurricane-force winds extending just 15 nautical miles (17 miles [28 km]) from the center.
Development
Irma originated as a tropical wave (an atmospheric trough or low air-pressure area) off the west coast of Africa on August 27. Conditions were favorable for storm development, with warmer-than-average seas and light winds in the upper atmosphere. By the time the wave reached the Cabo Verde Islands on August 30, it had strengthened to a tropical depression and became a tropical storm just six hours later. Irma intensified quickly because of low wind shear and warm seas, reaching hurricane status 30 hours later on August 31. At this point Irma was still located over the eastern Atlantic, 400 nautical miles (460 miles [741 km]) west of the Cabo Verde Islands.
Irma reached major hurricane status, with a wind speed of at least 100 knots (115 miles [185 km] per hour), on September 1—an increase of 70 knots (81 miles [130 km] per hour) in less than 48 hours. Such a rate of intensification is rarely seen in Atlantic tropical cyclones; only 1 in 30 generally accelerate at such a rate, according to the U.S. National Hurricane Center.
Irma fluctuated between a category 2 and category 3 hurricane until September 4, likely because of an influx of dry air and eyewall replacement cycles. (This is a process in which an outer eyewall, which is a broad ring of thunderstorms, contracts inward, cuts off inflow to the original smaller eyewall surrounding the eye of the storm, and ultimately replaces it.) A high-pressure system to its north caused Irma to turn west-southwestward, toward the Leeward Islands. It intensified to 155 knots (178 miles [287 km] per hour) on September 5, when it was just 70 miles (113 km) from Barbuda.
Irma made its first landfall as a category 5 storm on Barbuda at 1:45 am local time on September 6. Storm surge was significant, with estimates suggesting about 8 feet (2 meters) of water. Irma continued on to Saint Martin and Virgin Gorda that same day, with similar intensity, before weakening slightly as it approached Puerto Rico. Although Irma did not make landfall in Puerto Rico, it left drenching rain—10–15 inches (25–38 cm)—and the island was mostly without electricity and water for days.
The storm then passed over the Turks and Caicos and the Bahamas, making landfall on the latter as a category 4 hurricane at 1:00 am local time on September 8, thereby ending a 60-hour spree as a category 5 storm.
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About 18 hours later Irma restrengthened into a category 5 hurricane before making its fifth landfall in northern Cuba late on September 8, driving waves and seawater a half mile inland. Irma then tracked along Cuba, and the land interaction caused it to weaken to a category 2 about 15 hours later.
Once Irma’s core reached the warm Straits of Florida, it intensified again, becoming a category 4 storm on September 10, about 55 nautical miles (63 miles [102 km]) from Key West, before making its sixth landfall near Cudjoe Key about 9:00 am local time. High-water marks near Big Pine Key suggested a storm surge of about 8 feet (2 meters). Flooding in Miami was driven by a combination of heavy rain, urban runoff, and seawater intrusion into the city’s sewer systems.
Irma then dropped to a category 3 before making its final landfall near Marco Island a few hours later. It subsequently weakened to category 1 and widened before passing over much of central Florida, including Tampa and Orlando, with a wind field of 360 nautical miles (414 miles [667 km]) from the hurricane center. Everglades National Park and Ten Thousand Islands National Wildlife Refuge were in the path, and some estimates claim that as much as 10 feet (3 meters) of storm surge may have occurred there. By September 11 Irma had weakened to a tropical storm near Gainesville, with its strongest winds moving over northern Florida and southern Georgia. The system reached Alabama on September 12 with wind speeds of 25 knots (29 miles [46 km] per hour), and it dropped heavy rain on North Carolina and South Carolina as well. Remnant winds and rain reached southeast Missouri the next day.
Damage
Hurricane Irma caused immense property damage, estimated between $64 billion and $90 billion. The U.S. alone incurred damage close to $50 billion, which makes Irma one of the costliest tropical cyclones in the country’s history. In the United States and the Caribbean, 47 direct deaths were reported, most of which were attributed to drowning or wind-related accidents. An additional 82 indirect deaths were reported in the United States, with 77 of these occurring in Florida. Irma struck many small islands in the Caribbean at peak or near-peak intensity. Barbuda was devastated, with nearly 95 percent of structures affected, leaving the island nearly uninhabitable. Survivors sought shelter on its sister island of Antigua, 25 miles (40 km) away. Economic costs for rebuilding were estimated at more than $222 million.
Satellite imagery from the British Virgin Islands and the U.S. Virgin Islands taken after Irma revealed widespread deforestation, showing swaths of empty, brown landscape, as Irma’s wind had stripped the land of vegetation. In Cuba, Irma—the first category 5 hurricane to hit the island directly since 1924—damaged more than 150,000 homes. Nearly 15,000 of those were completely destroyed.
The Bahamas had ordered the largest evacuation in the country’s history ahead of Irma’s arrival, and the central and northwestern Bahamas lay well beyond Irma’s most powerful winds. However, many of the islands still saw tropical storm conditions and sustained minor damage. Seventy percent of the houses on Great Inagua Island were reportedly damaged.
In the United States Irma hit less than two weeks after Hurricane Harvey, marking the first time the continental U.S. had seen two category 4 storms in one season since recordkeeping began in 1851. The storm produced 21 tornadoes in Florida and 4 in South Carolina. More than 6 million Florida residents were evacuated, one of the largest evacuations in U.S. history. Most of the structural damage was confined to the Florida Keys, with 25 percent of buildings destroyed. Irma also affected the agricultural industry; losses in this sector were estimated at $2.5 billion.
Aftermath
Irma left lasting effects on the communities in its path. By 2025 most displaced residents of Barbuda had returned, but in the wake of the destruction, disputes over communal land ownership intensified. Many residents alleged that the government was using the hurricane’s aftermath as an opportunity to pursue billionaire-investor-friendly development, challenging the island’s long-standing system of collective land rights.
In the United States the Federal Emergency Management Agency (FEMA) deployed emergency housing units and funded road and utility repairs, in addition to distributing more than $48 million in aid to survivors. Recovery in Florida was a complex, long-term effort, with housing shortages and infrastructure strain complicating the issue. Physical and mental health conditions of evacuees and survivors were adversely affected, and the worsening of respiratory problems, anxiety, and depression were reported even 20 months after the hurricane.
Almost 60 percent of the Florida Everglades sustained serious damage. The damage to the mangroves, pinelands, and hardwood hammocks, which are the preferred habitats of the Florida Key deer (Odocoileus virginianus clavium), resulted in a 23 percent decline in the animal’s population.