Hurricane Helene ( heh-LEEN) was a powerful and devastating tropical cyclone that caused widespread catastrophic damage and numerous fatalities across the Southeastern United States in late September 2024. It was the strongest hurricane on record to strike the Big Bend region of Florida, the deadliest Atlantic hurricane since Hurricane Maria in 2017, and the deadliest to strike the mainland U.S. since Hurricane Katrina in 2005.
The eighth named storm, fifth hurricane, and second major hurricane of the 2024 Atlantic hurricane season, Helene began forming on September 22, 2024 as a broad low-pressure system in the western Caribbean Sea. By September 24, the disturbance had consolidated enough to become a tropical storm as it approached the Yucatán Peninsula, receiving the name Helene from the National Hurricane Center. Weather conditions led to the cyclone's intensification, and it became a hurricane early on September 25. More pronounced and rapid intensification ensued as Helene traversed the Gulf of Mexico the following day, reaching Category 4 intensity on the evening of September 26. Late on September 26, Helene made landfall at peak intensity in the Big Bend region of Florida, near the city of Perry, with maximum sustained winds of 140 mph (220 km/h). Helene weakened as it moved quickly inland before degenerating to a post-tropical cyclone over Tennessee on September 27. The storm then stalled over the state before dissipating on September 29.
Helene's precursor and early stages caused flooding in Nicaragua, Honduras, the Cayman Islands, and the Yucatán Peninsula, where high winds left more than 120,000 customers without electricity in Quintana Roo. Storm surge in Florida caused significant damage from the Tampa Bay area northward. Hillsborough and Pinellas counties combined reported the destruction of at least 419 residences, major damage to at least 18,512 structures, and minor to moderate damage to 13,909 others. Several counties in or near the Big Bend suffered extensive wind impacts. Heavy crop and timber losses occurred over southern Georgia, totaling about $5.5 billion. Tens of thousands of homes and buildings suffered wind damage as far north as the Augusta area, while floodwaters entered at least 200 structures and a number of vehicles in the Atlanta area. Catastrophic flooding and more than 2,000 landslides occurred over the southern Appalachian Mountains, especially North Carolina, due to rainfall totals up to 30.78 in (782 mm) in Busick, North Carolina. In North Carolina, over 125,000 housing units and approximately 822,000 acres (333,000 ha) of timberland suffered some degree of damage. Thousands of miles of bridges and roads were damaged by floodwaters. At least 106 fatalities occurred in North Carolina, far more than any other state. Helene and its remnants also spawned thirty-nine tornadoes across the United States, one of which killed two people in Wheeler County, Georgia. Flooding also impacted Virginia, West Virginia, and Ohio, leaving 12 homes destroyed and 104 others damaged in Pulaski County, Virginia, alone. More than 7.4 million customers lost electricity across the United States. At least 253 deaths and $78.7 billion in damages have been attributed to Helene, making it the second-deadliest hurricane to strike the continental United States in fifty years, after Katrina in 2005, and the deadliest overall since Maria in 2017, as well as being the fifth costliest hurricane in the United States.
Meteorological history
On September 17, 2024, the National Hurricane Center (NHC) highlighted the potential for tropical cyclogenesis in the western Caribbean Sea. Conditions conducive for development of a tropical cyclone resulted from the interaction of the Central American gyre—a broad monsoon low pressure system—and the Madden–Julian oscillation, which reinforced the large-scale cyclonic flow extending from the eastern Pacific Ocean to the western Caribbean Sea. Several days later, on September 22, a broad low-pressure area developed within the western Caribbean. As the system traversed an environment conducive for tropical cyclone development, showers and thunderstorms associated with the disturbance gradually consolidated. Due to the system's imminent threat to land, it was designated Potential Tropical Cyclone Nine on September 23. The next day, Air Force Reserve Hurricane Hunters aircraft and satellite data indicated that a low-level center had formed by 12:00 UTC, leading to the NHC to upgrade the system to Tropical Storm Helene with maximum sustained winds of 45 mph (72 km/h). The system continued strengthening, becoming a hurricane by 12:00 UTC on September 25 as it entered the Gulf of Mexico while turning north. An upper-level trough to its west and a ridge of high pressure located off the Southeastern United States both served to steer the cyclone towards the U.S. Gulf Coast. Helene was an extensive system, with the NHC noting in multiple forecast discussions that the forecast storm radii were "at the 90th percentile of hurricane size at similar latitudes".
After remaining steady in intensity for a while due to its broad size and some entrainment of drier air to its west, Helene rebounded on the morning of September 26. Aided by low mid-level wind shear, high relative humidity, and sea surface temperatures exceeding 86 °F (30 °C) near the Loop Current, the system began to rapidly intensify. An increasingly defined eye developed, and Helene reached Category 2 intensity at 12:00 UTC. By 18:00 UTC, Helene strengthened to a Category 3 major hurricane, with sustained winds up to 120 mph (190 km/h). At 00:00 UTC on September 27, the hurricane attained its peak intensity with maximum sustained winds of 140 mph (220 km/h) and a minimum barometric pressure of 939 millibars (27.73 inHg). Retaining this intensity, it made landfall about 10 miles (16 km) west-southwest of Perry, Florida at 3:10 UTC, becoming the strongest hurricane to strike Florida's Big Bend region since records began in 1900. Rapid weakening occurred as the storm tracked inland, and it weakened to a Category 2 hurricane at 5:00 UTC shortly after crossing into Georgia. Weakening further, it became a tropical storm over east central Georgia at 9:00 UTC. Helene transitioned to a post-tropical cyclone at 18:00 UTC by September 27 in southern Kentucky, with the system losing deep convection and merging with a cut-off low to its west. After executing a slow-cyclonic loop, remnants of Helene dissipated at 18:00 UTC on September 28 over north-central Tennessee.
As Helene moved north into the Southern Appalachian Mountains, the storm would encounter the terrain of the Blue Ridge and Black Mountains. As it passed through, there was a significant and noticeable amplifying of rainfall, as well as a rapid increase in cooling, condensation and precipitation in the region.
Influence of climate change
On October 9, researchers with World Weather Attribution concluded with "high confidence" that Helene was made worse by climate change. In a scientific assessment, researchers found the 2.3 °F (1.3 °C) increase in temperatures due to climate change increased Helene's rainfall by 10% and maximum wind speeds by 11%, or 13.6 mph (22 km/h), as compared to a similar storm in prior cooler conditions.
Preparations
Mexico
Tropical storm warnings were issued on September 24, 2024, for the eastern Yucatán Peninsula. Parts of Quintana Roo and Yucatán were placed under a blue alert, indicating indirect impacts. It was later raised to red alert, maximum danger. Cruise ship arrivals in the former state's ports were canceled for September 24 and 25. Tren Maya was also closed. On Isla Mujeres, two shelters were opened. Evacuations were carried out in vulnerable areas. Visitors of Isla Holbox were offered a ferry ride off the island at no cost. Classes were suspended in Quintana Roo.
Caribbean
Cayman Islands
The Cayman Islands were under a tropical storm warning on September 24. The Cayman Islands' Red Cross shelter opened in preparation for the storm; nobody used it. Sandbagging sites opened on Grand Cayman and Cayman Brac. Due to the threat of heavy rainfall, schools in the Cayman Islands were closed on September 23. Charles Kirkconnell International Airport and Owen Roberts International Airport were closed ahead of Helene's arrival. The Cayman Islands Regiment was deployed ahead of the system to help with the preparation and distribution of sandbags. Additionally, a small craft warning was issued for the islands on September 23, with a marine advisory issued the next day. The tropical storm warning was canceled the next day.
Cuba
Tropical storm warnings and hurricane watches were issued for western Cuba. Medical brigades were prepared for flood-prone areas; as heavy rain began to fall, schools and ports were closed, and fishing boats were called in. Due to adverse weather conditions caused by Helene, the Provincial Transport Company of Havana suspended ferry services in Regla. Additionally, the Maritime Administration of Cuba suspended navigation in the Gulf of Batabanó.
United States
Amtrak modified or canceled several of its southeastern train routes between September 27 and October 1 because of the storm.
Florida
Hurricane warnings were issued for the Big Bend area of Florida, and the entire state except the westernmost part of the Florida panhandle was put under a tropical storm warning. In addition, on the evening of September 26, an extreme wind warning was issued for the east part of the Florida panhandle, the first since Hurricane Idalia. On September 23, Ron DeSantis, the governor, issued a state of emergency for 41 of Florida's 67 counties. The next day, this was expanded to 61 counties. U.S. President Joe Biden authorized a federal disaster declaration for 61 counties across Florida. Locally, Volusia County issued a state of emergency. Several sandbagging sites opened up across the state. On September 24, several state parks were closed: four of them in Franklin County, two in Gulf County, and one in Gadsden County.
In the Tampa Bay area, officials announced that schools would be closed ahead of the storm. A college football game between Florida A&M University and Alabama A&M University, which was scheduled for the weekend of September 28–29, was postponed until November 29 due to the storm. At Florida State College at Jacksonville, classes and activities at the campus were canceled for two days. The SpaceX Crew-9 mission, which would have launched from the Cape Canaveral Space Force Station on September 26, was delayed to September 28 due to the storm. The Central Florida Zoo and Botanical Gardens planned to close on September 26 and canceled events on that date.
Mickey's Not-So-Scary Halloween Party was canceled due to Helene, with SeaWorld Orlando and several other parks in Walt Disney World and Universal Orlando also closing or modifying their hours. Halloween Horror Nights was also canceled. The universities of Central Florida, Embry–Riddle Aeronautical, Florida, Florida A&M, Florida Atlantic, Florida Gulf Coast, Florida State, Keiser, Lynn, North Florida, South Florida, and Stetson announced closures of their campuses and suspended academic operations. Leon County opened up schools to be used as shelters.
On September 24, Citrus County issued mandatory evacuations for zone A, which includes coastal areas in the communities of Crystal River and Homosassa. In Wakulla County, a mandatory evacuation was ordered for all residents and visitors. In contrast, in Hernando County, mandatory evacuations were ordered for anyone west of US 19 and all residents in coastal or low-lying areas and those living in manufactured homes. Two prisons in Wakulla County holding a combined 2,500 inmates were not evacuated despite the evacuation order issued to residents. Gulf County issued mandatory evacuations for all visitors. In Charlotte County and Franklin County, mandatory evacuations were issued for barrier islands, low-lying and flood-prone areas, manufactured homes, and homes that did not meet building codes. In Sarasota County, officials issued an evacuation order for Level A and manufactured home communities on September 25.
Busch Gardens Tampa Bay, St. Pete–Clearwater International Airport, and Tampa International Airport were closed on September 26. Further north, Tallahassee International Airport was closed the same day.
Prior to Helene's landfall, residents in Florida showed the highest level of perception of disaster likeliness at 84% believing that there would likely be a major meteorological event, according to a 2023 FEMA National Household Survey. Despite this, there was also a relatively low preparedness rate within the state, with only about 47% of residents saying that they believed they could stay home in case of a major meteorological event.
Georgia
The coast of Georgia was placed under tropical storm warnings. In contrast, southwestern Georgia was placed under a hurricane warning which extended as far north into the state as Spalding County, and all tropical storm watches in Georgia were replaced with tropical storm warnings as far north as the Tennessee and Georgia state border. The National Weather Service in Peachtree City accidentally issued a hurricane warning for Jackson County when it was supposed to be a tropical storm warning.
In addition, on the night of September 26, an extreme wind warning was issued for portions of southern Georgia, including Valdosta. On September 24, in preparation for Helene, officials in the counties of Bryan, Candler, and Chatham began mobilizing emergency response centers. Colquitt, Thomas, and Decatur counties opened shelters. On the same day, Governor Brian Kemp issued a state of emergency for Georgia since Helene was expected to track into the state. In Thomas County, the Public Works Department began providing sandbags due to the storm.
On September 25, schools were closed in the counties of Bibb and Twiggs. Many schools in the Atlanta metropolitan area canceled instruction for September 26 and 27, such as Atlanta Public Schools, with some counties moving students and non-essential workers online. Also, some schools went to a digital learning day, for example, Gwinnett County Public Schools had a digital learning day on the 26th and was canceled altogether on the 27th. Elsewhere, in Clayton County, schools and indoor and outdoor athletic events were canceled. The Cumberland Island National Seashore and Fort Pulaski National Monument closed on September 25 in preparation for the hurricane. The Atlanta Braves postponed the remaining two games in a series against the New York Mets to September 30 in a doubleheader. Curfews were implemented by several localities on September 26. Emory University moved classes online for September 26 and 27, and the University of Georgia cancelled classes entirely. Ahead of the storm, vice-presidential nominee JD Vance canceled two events on September 26 for the 2024 Trump–Vance campaign scheduled in Macon and Flowery Branch.