World Meteorological Organization

• 1. Introduction

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  The World Meteorological Organization exists because weather has never respected borders. Rain clouds forming over one country deliver their consequences in another. Storms that begin over open ocean arrive at coastlines that belong to sovereign states. Long before satellites, before computers, before any of the institutions we now take for granted, scientists understood that tracking the atmosphere meant sharing information across political lines.

  What eventually became the WMO began not as a government program but as a gathering of scientists, nearly a century and a half ago. The path from that first informal network to a formal United Nations agency runs through a naval officer named Matthew Fontaine Maury, a convention signed in 1947, and a specific date in March 1950 when everything changed. Today 193 countries and territories belong to the organization, and their meteorological services exchange data under a mandate described as "free and unrestricted."

  How does a body that coordinates between nearly every nation on Earth actually work? What does it publish, what does it measure, and why does a prize for climate science trace back to its founding partnership with the United Nations Environment Programme?

• 2. From Telegraph to Treaty

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  Matthew Fontaine Maury, an officer with the US Navy, called the world's meteorologists together for the first true international meteorological conference from late August through early September 1853. That gathering planted the seed for everything that followed. International cooperation on weather reporting had been attempted as far back as the 1600s, but the invention of the telegraph in 1843 made systematic global data exchange practically possible for the first time.

  The 1853 conference led directly to the foundation of the International Meteorological Organization in 1873. The IMO was a nongovernmental body, a forum built by scientists rather than states, and it operated that way for decades. Its work during the nineteenth and early twentieth centuries produced the physical and digital books, pamphlets, maps, and graphs that now constitute the IMO Legacy Collection, which was inscribed on UNESCO's Memory of the World International Register in 2025 and is currently being digitized and made available through WMO's e-Library.

  The shift from nongovernmental forum to intergovernmental agency required a formal legal instrument. Proposals to restructure the IMO culminated in the World Meteorological Convention, signed on the 11th of October 1947. That convention entered into force on the 23rd of March 1950, and within a year the WMO had begun operations as a recognized body within the United Nations System. The 23rd of March is now observed annually as World Meteorological Day.

• 3. How the WMO Governs

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  The World Meteorological Congress is the supreme body of the organization, and every member state and territory sends a Permanent Representative when it convenes. Congress meets every four years to set policy and priorities, and it elects the President and vice-presidents, selects the members of the Executive Council, and appoints the Secretary-General.

  The Executive Council implements the decisions Congress makes. Beneath it, the Secretariat runs day-to-day operations. It is an eight-department organization with a staff of 200, led by a Secretary-General who can serve no more than two four-year terms.

  The office of Secretary-General has changed hands several times since Gustav Swoboda of Switzerland held it from 1952 to 1955. David Arthur Davies of the United Kingdom then served from 1956 to 1979, the longest tenure in the organization's history. Aksel C. Wiin-Nielsen of Denmark followed from 1980 to 1983, and Godwin Obasi of Nigeria held the position from 1984 to 2003. The current Secretary-General is Celeste Saulo of Argentina, who took office in 2024. The current President is Abdulla Al Mandous of the UAE.

• 4. The Language of Weather Data

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  Sharing weather observations across 193 member states requires a shared language, and the WMO maintains that language through a system of standardized code forms. The traditional forms, including SYNOP, CLIMAT, and TEMP, are character-based and use positional coding, meaning the location of a character within the message determines what it represents.

  Newer code forms were designed for portability, extensibility, and universality. BUFR handles a wide range of meteorological, oceanographical, and hydrological data. GRIB is specifically designed for gridded geo-positioned data, the kind used in numerical weather prediction.

  The WMO also sets the standard units that member services use when exchanging observations. Temperature goes in degrees Celsius or Kelvin. Wind speed is expressed in metres per second. Atmospheric pressure is measured in hectopascals. Cloud cover uses a unit called oktas. The WMO states that the International System of Units should serve as the standard for meteorological elements exchanged internationally, though it formally endorses some units that fall outside the strict SI definition.

• 5. Climate on the Record

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  Each year the WMO publishes its Statement on the Status of the World Climate, which documents global, regional, and national temperatures alongside extreme weather events. The statement also tracks long-term indicators including atmospheric concentrations of greenhouse gases, sea level rise, and sea ice extent. According to the most recent report available in the source, 2016 was the hottest year on record, marked by widespread weather and climate extremes.

  The WMO's work on climate science connects to one of the most prominent scientific recognitions in recent history. The Intergovernmental Panel on Climate Change, the IPCC, was created jointly by the WMO and the United Nations Environment Programme, known as UNEP. In 2007, the IPCC received the Nobel Peace Prize for efforts to build up and spread knowledge about anthropogenic, or human-caused, climate change, and for laying the groundwork for measures to counteract it.

  Beyond the annual climate statement, the WMO publishes a Greenhouse Gas Bulletin annually and releases the WMO Bulletin twice a year. In September 2020, it published the United in Science 2020 Report, a high-level compilation drawing on contributions from the WMO, the Global Carbon Project, UNESCO-IOC, the IPCC, UNEP, and the Met Office. That report is divided into seven chapters, each with a set of key messages.

• 6. Who Belongs and Who Does Not

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  As of 2023, the WMO counts 187 member states and 6 member territories, for a total membership of 193. The six member territories are the British Caribbean Territories, French Polynesia, Hong Kong, Macau, Curaçao and Sint Maarten as a joint membership, and New Caledonia.

  Eight United Nations member states fall outside the WMO's membership: Equatorial Guinea, Grenada, Liechtenstein, the Marshall Islands, Palau, Saint Kitts and Nevis, Saint Vincent and the Grenadines, and San Marino. Two WMO members, Cook Islands and Niue, are not members of the United Nations. Vatican City, the State of Palestine, and states with limited international recognition belong to neither organization.

  Membership is organized into six regional associations. Africa forms Region I with 57 member states. Asia is Region II with 33 member states and 2 member territories, Hong Kong and Macau among them. South America makes up Region III with 13 member states. Region IV covers North America, Central America, and the Caribbean, with 25 member states and 2 member territories. The South-West Pacific is Region V with 23 member states and 2 member territories. Europe and parts of Western Asia form Region VI with 50 member states. Ten member states hold membership in more than one region; two of those belong to four different regions simultaneously.