Hurricanes, Typhoons and Cyclones

Hurricanes, typhoons and cyclones pose significant global threats to life and property, including storm surges, flooding, extreme winds and tornadoes.

Additionally, rainfall rates are projected to increase in the future due to anthropogenic warming and accompanying increase in atmospheric moisture content.

According to the National Hurricane Center (NHC), “A tropical cyclone is a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has a closed low-level circulation.”

Hurricanes, cyclones and typhoons are different terms for the same weather phenomenon. The World Meteorological Organization (WMO) describes the terms in the following manner:

• “In the western North Atlantic, central and eastern North Pacific, the Caribbean Sea and the Gulf of Mexico, such a weather phenomenon is called hurricanes.
• In the western North Pacific, it is called typhoons.
• In the Bay of Bengal and the Arabian Sea, it is called cyclones.
• In western South Pacific and southeast Indian Ocean, it is called severe tropical cyclones.
• In the southwest India Ocean, it is called tropical cyclones.”

As a storm moves across the ocean, it picks up warm, moist air from the surface and dispenses cooler air aloft. As the storm makes landfall, it loses momentum, no longer fueled by the warm ocean air. Winds of up to 185 miles per hour are just one damaging aspect. Drenching rains can cause heavy flooding inland. Wind-driven storm surges also can dangerously inundate low-lying areas.

The Saffir-Simpson Hurricane Wind Scale is a one to five rating based on a hurricane’s maximum sustained wind speed. However, this rating system faces some controversy because it does not always capture the storm’s full potential impact, which may be caused by rain and flooding. This rating system does estimate potential property damage.

Hurricane Ida is an example of a cyclone that demonstrated repeated cycles of strengthening and weakening as it moved across a large geographic area from Cuba to Louisiana to New York. Ida produced a devastating storm surge that moved inland from the immediate coastline across portions of southeastern Louisiana. Most hurricanes quickly weaken upon landfall, but Ida remained a major hurricane for nine hours. As the world warms, it is expected that more tropical systems will use the warmer water to intensify rapidly. Ida went from showers to a 150-mile-per-hour hurricane in three days.

Rapid intensification of tropical systems is a growing concern. NOAA defines rapid intensification as a storm that increases by 35 miles per hour within a 24-hour period. In 2022, Hurricane Ian grew from a tropical storm to a Category 3 hurricane within 36 hours. It then grew to a Category 4 the next day – gaining 35 miles per hour within just three hours – and reached Category 5 strength a few hours later. Similarly, in September 2022, on the other side of the world, Typhoon Noru grew from a Category 1 equivalent to a Category 5 equivalent in just six hours, leaving residents of the Philippines no time to prepare or evacuate.

A tropical cyclone may occur somewhere in the world throughout the year. According to the WMO, “The typhoon season in the western North Pacific region typically runs from May to November. The Americas/Caribbean hurricane season runs from June 1 to November 30, peaking in August and September. The cyclone season in South Pacific and Australia normally runs from November to April. In the Bay of Bengal and Arabian Sea, tropical cyclones usually occur from April to June, and September to November. The East Coast of Africa normally experiences tropical cyclones from November to April.” Discussions among experts are ongoing about whether the start and end dates of these traditional seasons need to be revised.

Hurricane forecasting continues to improve in accuracy and in its ability to provide advance warning. However, it remains an inexact science because of the number of factors that can influence a hurricane’s direction and strength, including wind speed, size, rainfall and duration.

In the U.S., the NHC provides the public and its partners with information on tropical weather, including forecasts. The NHC is a division of NOAA and is located at Florida International University in Miami, Florida.

The NHC uses many models in the preparation of forecasts. However, they state, “Users should also be aware that uncertainty exists in every forecast, and proper interpretation of the NHC forecast must incorporate this uncertainty.”

Globally, early-stage formation is monitored by WMO through its World Weather Watch and Tropical Cyclone Programmes. WMO regional centers provide, in real-time, advisory information and guidance to the National Meteorological Services. The National Meteorological Services of countries then issue official warnings.

• To be classified as a hurricane, typhoon or cyclone, tropical systems must reach wind speeds of at least 73 miles per hour (118 kilometers per hour). If winds speeds are below 73 miles per hour, the storms are classified by different terminology based on the location. For example, in the North Atlantic and northeast Pacific, a storm with winds speeds less than 73 miles per hour is called a tropical storm or a tropical depression if wind speeds are 32 miles per hour (62 kilometers per hour) or less.
• Tropical cyclones produce widespread and devastating impacts. Historically, the costliest disasters have been hurricanes, often those occurring in the U.S., and earthquakes. Hurricane Ian hit the U.S. in 2022 causing damages worth $100 billion, making it the costliest disaster event globally that year. Of the 387 disasters worldwide recorded by the Emergency Event Database EM-DAT in 2022, 108 were storms.
• More people are living in harm’s way. According to the U.S. Census Bureau, 128 million people, or more than 40% of the total U.S. population, lived in coastline counties in 2018. Of those in the continental U.S. about 19 million people live within .62 of a mile (one kilometer) from the coast and 11.6 million people live below 9.8 feet (3 meters) of elevation. The Center for International Earth Science Information Network at Columbia University says around 40% of the world’s population (or 2.4 billion people) lives within 62 miles (100 kilometers) of the coast. The world is urbanizing, and coastal cities face worrying levels of exposure vulnerability to natural hazards, including tropical cyclones.
• Tropical cyclones are increasing in intensity because of climate change. Heat trapped by greenhouse gases released by human activities gets stored in oceans, providing additional fuel for hurricanes. Major tropical cyclones pose a significant threat to life and property, and studies suggest that increased tropical cyclone intensity is likely under continued warming.
• Tropical cyclones can produce health impacts. According to the World Health Organization, tropical cyclones may affect health in many ways, such as increasing risks of water-borne diseases, increasing mental health effects, and disrupting health systems. A 2022 study found that hurricanes and other tropical storms in the U.S. were associated with up to 33.4% higher death rates in subsequent months. Tropical cyclones, including hurricanes, can also cause people to experience emotional distress.
• Tropical cyclones bring more rainfall, increasing flood risks. Because warmer air contains more moisture, as surface temperatures rise, rainfall rates are increasing. In addition, changes in circulation patterns cause hurricanes to move slower, meaning more rainfall in a single location, as with Hurricane Harvey in 2017. The National Weather Service had to add two shades of purple to its map to show the amount of rainfall due to Harvey. Hurricane Florence was only a Category 1 hurricane when it made landfall in North Carolina in September 2018, but the slow-moving storm brought heavy rain to the Carolinas, flooding tens of thousands of homes.

• Invest in local organizations. In the U.S., long-term recovery groups provide coordinated services to enable everyone to recover. Building the capacity of such organizations with a long-term presence at the local level helps ensure preparedness and recovery efforts are contextually relevant and effective. Local communities and actors know their context and needs best. Outside the U.S. localization is a term used to describe the process of recognizing, respecting and strengthening local capacity to better address the needs of affected people.
• Support tropical cyclone preparedness. Creating evacuation plans, assembling disaster supplies and retrofitting homes can help lessen the impact of a tropical storm. Preparedness support is essential for low-income individuals and marginalized populations. Ensure that communication materials are culturally appropriate and in the local population’s preferred language(s).
• Support mental health and psychosocial support programs. Not all tropical cyclone damage is visible. Exposure to hurricanes is a risk for new-onset major depression, generalized anxiety disorder and post-traumatic stress disorder. Mental health support and care are needed in preparedness and recovery. This is particularly true in areas that have experienced multiple storms.
• Fund efforts to protect and improve natural barriers in coastal areas. Natural features such as marshes, wetlands, mangroves and coral reefs are a primary line of defense against the coastal hazards of hurricanes, typhoons and cyclones. In Louisiana, the Coastal Master Plan has provisions to create or restore almost 34,000 acres of marsh that make up a land bridge buffer. According to the World Bank, integrating “green” infrastructure, such as mangroves, with traditional “gray” infrastructure like embankments can provide cost-effective protection from tropical cyclones.

• The Center for Disaster Philanthropy (CDP) has a standing Atlantic Hurricane Season Recovery Fund. CDP also makes grants in support of tropical cyclone recovery and preparedness through the Global Recovery Fund, the Disaster Recovery Fund and in partnership with Google. The following are examples of related grantmaking.
  • $250,000 to Collier Disaster Alliance to support survivors of Hurricane Ian in Collier County, Florida, through community collaboration, casework, case management partnership, volunteer labor organization, referrals, information sharing, financial repair and rebuild assistance, and allocating financial aid to individuals through unmet needs allocations.
  • $450,000 to Equal Justice Works to enhance capacity to deliver legal services by mobilizing legal fellows to partner organizations in Florida and Puerto Rico to serve low-income communities impacted by Hurricanes Ian and Fiona and at risk of future disaster.
  • $250,000 to Fundación de Mujeres en Puerto Rico to support local, women-led and women-serving organizations in some of Puerto Rico’s most marginalized communities affected by Hurricane Ian.
  • $300,000 to Habitat for Humanity Florida to provide long-term assistance to Hurricane Ian-affected local Habitat affiliates with funding to repair and rebuild low-income households, helping affected families and children return to safe and secure homes.
  • $200,000 to Hope DeSoto Long Term Recovery Group (through fiscal agent Arcadia-DeSoto County Habitat for Humanity) to increase long-term recovery efforts in DeSoto County, Florida, necessitated by Hurricane Ian and to build community resiliency.
  • $98,872 to Philippine Disaster Resilience Foundation to restore livelihoods through providing resilient livelihood starter kits and training on boat building to fishing communities affected by Typhoon Odette in Siargao and Dinagat islands.
• In 2022, The Walmart Foundation made an investment of more than $3 million in a group of organizations helping local government leaders and community-led organizations in the Gulf Coast prepare their communities for disasters.
• The Gulf Coast Community Foundation provided more than $3 million in immediate relief to organizations working in areas hard hit by Hurricane Ian. The grants focused on health and human service needs in southern Sarasota County including Venice, North Port, Englewood, Charlotte County, Lee County and DeSoto County.
• The Community Foundation of Sarasota County (CFSC) activated the Suncoast Disaster Recovery Fund to address long-lasting impacts of Hurricane Ian on people’s lives. The fund supports Sarasota, Manatee, DeSoto and Charlotte Counties for disaster recovery to improve individual, family and community resiliency. The Patterson Foundation strengthened the fund by providing an immediate $500,000 gift to catalyze donor support and a match for all donations up to $750,000. CFSC took time to listen to local organizations and community leaders, which informed what the foundation will focus their resources on to support long-term recovery.

• The National Hurricane Center (NHC)
• NHC: Cone of Uncertainty
• University of Rhode Island: Hazards and Impacts of Hurricanes
• Ready.Gov: Hurricanes
• NHC: Worldwide Tropical Cyclone Centers
• Australian Government Bureau of Meteorology: About Tropical Cyclones
• United Nations Office for Disaster Risk Reduction: Cyclone
• World Health Organization: Tropical Cyclones
• World Meteorological Organization: Tropical Cyclones
• Substance Abuse and Mental Health Services Administration: Hurricanes and Tropical Storms

We welcome republication of our content. Please credit the Center for Disaster Philanthropy.

(Photo: Destruction can be seen from the air in and around Marathon, Florida as recovery efforts continue following Hurricane Irma. Credit: U.S. Customs and Border Protection photo by Kris Grogan)