A tropical cyclone is a cyclone of tropical origin of small diameter (some hundreds of kilometres) with a minimum surface pressure in some cases of less than 900 hPa, very violent winds and torrential rain; sometimes accompanied by thunderstorms. It usually contains a central region, knows as the ‘eye’ of the storm, with a diameter of the order of some tens of kilometres, and with light winds and a more of less lightly clouded sky (WMO, 2017).

Hurricanes, tropical cyclones and typhoons affect millions every year, and are likely to become more severe in the future although possibly less frequent due to global warming.

Tropical cyclones, hurricanes and typhoons, although named differently, describe the same hazard type. They are referred to as tropical cyclones in the Indian Ocean and South Pacific, hurricanes in the Atlantic and eastern North Pacific, and typhoons in the western North Pacific. In the north Atlantic and the Caribbean, August and September are usually peak months of the hurricane season, which spans from June through to November. In the eastern North Pacific, the season starts in mid-May and finishes in November. The North Indian Ocean cyclone season is between April and December, with peaks in May and October.

Tropical cyclones are often difficult to predict, because they can suddenly weaken or change their course. However, meteorologists use state-of-art technologies and develop modern techniques such as numerical weather prediction models to predict how a tropical cyclone evolves, including its movement and change of intensity, when and where one will hit land and at what speed. Official warnings are then issued by the National Meteorological Services of the countries concerned (WMO).

Risk factors

  • Climate change: Due to warmer global temperatures, the proportion of high-intensity cyclones has increased. Also, cyclones are likely to move slower on land, and thus become more devastating.
  • Environmental degradation: Deforestation creates a warm area that draws in sea breezes from the ocean during the daytime, producing moisture, and leading to storms. In turn, rising waters can make wastewater treatment plants, sewers, hazardous waste sites, agricultural lands and animal feeding operations overflow, carrying pollutants into waterways.
  • Coastal development, including urbanization in coastal areas: Apart from increasing its exposure to coastal hazards, a city’s impervious sidewalks and streets increase, heavy rainfall can not be absorbed into the ground.

Vulnerable areas

  • Coastal areas are the most cyclone-prone.
  • Tropical cyclones are generally accompanied with heavy rains and severe flooding.
  • Coastal areas with shallow slant bathymetry and flat plain, with storm surges that may threaten tens of thousands of people living by the sea.
  • The most vulnerable populations are those who are living in poor buildings and fragile constructions in the coastal zones.
  • The Small Island Developing States are also vulnerable because some might be indebted, their economies undiversified and hazard events can affect the whole territory.

Saffir-Simpson hurricane scale

Hurricanes are ranked according to the Saffir-Simpson hurricane scale, which classifies the damage caused by hurricanes to wind speed. Hurricanes can inflict terrible damage even from their formative stage.

Risk reduction measures

  • Evacuation exercises to ensure full community participation.
  • Structural measures to withstand/lessen the impact of winds and flooding.
  • Land use control and limiting the exposure of critical assets.
  • Integrate flood risk assessment into urban planning strategies.
  • Avoid building directly on the coastline.
  • Maintain wind-proof buildings for community shelters.
  • Use of flood-resistant material in construction.
  • Grey infrastructure: sea walls revetments, protective embankments, levees and dikes.
  • Natural infrastructure: mangroves, coral reefs, wetlands and forests.
  • Education: information on cyclones and protection from cyclone damage in school and social activities.
  • Protect and evacuate animals.

Latest Cyclone additions in the Knowledge Base

Destruction of Hurricane Beryl
One week after the storm, communities are coming to terms with the full extent of Hurricane Beryl’s destruction. And hurricane season is far from over.
International Federation of Red Cross and Red Crescent Societies (IFRC)
Research briefs
Wilfires not only pose hazards to communities and wildlife with destruction of habits and infrastructure, but also affect public health, as well as impacting solar radiation and albedo feedbacks that link to global temperatures and meteorological cycles.
PhysOrg, Omicron Technology Ltd
AGU Advancing Earth and Space Science
Rising ocean heat poses new threats in terms of damaging hurricanes—some scientists have called for a new “category 6” classification to be added to storms above 192mph.
Bulletin of the Atomic Scientists
Research briefs
An international team of researchers are improving scientific understanding of atmospheric waves in the tropics, including how they impact extreme weather events like hurricanes and heavy rainfall.
The Rosenstiel School of Marine, Atmospheric, and Earth Science
Flood waters remain, and the full impact of Beryl is yet to be assessed. But one thing is clear, the cost will be far higher than these countries and their citizens can afford.
Conversation Media Group, the
A satellite observes a hurricane from space
In a significant breakthrough for real-time environmental monitoring and disaster response, Space Park Leicester has successfully utilised its advanced satellite system to capture near real-time images of Hurricane Beryl.
University of Leicester
Palms in a storm at the coast.
Research briefs
Rowan University climate scientist Dr. Andra Garner last year documented in the journal Scientific Reports that Atlantic Hurricanes, like the current storm Beryl, have developed faster and with greater strength over the past 50 years.
Rowan University
A stack of sandbags in front of a door.
CCRIF SPC made a payout on July 1, 2024, of US$6,376,184 to the Government of Guatemala on its excess rainfall policy following heavy rains that occurred during June 13th-19th.
Caribbean Catastrophe Risk Insurance Facility, the
Uploaded on

Is this page useful?

Yes No
Report an issue on this page

Thank you. If you have 2 minutes, we would benefit from additional feedback (link opens in a new window).