The WMO was established by the Convention of the World Meteorological Organization, signed 11 October 1947 and ratified on 23 March 1950. The Convention serves as the constituent treaty of the WMO, setting forth its purposes, governance, and general framework.

The WMO hierarchy:

• The World Meteorological Congress, the supreme body of the Organization, determines policy. Each member state and territory is represented by a Permanent Representative with WMO when Congress meets every four years. Congress elects the President and vice-presidents of the Organization and members of the Executive Council; and appoints the Secretary-General.
• The Executive Council (EC) implements Congress decisions.
• The Secretariat is an eight-department organization with a staff of 200 headed by a Secretary-General, who can serve a maximum of two four-year terms.^[9]

The annually published WMO Statement on the status of the World Climate provides details of global, regional and national temperatures and extreme weather events. It also provides information on long-term climate change indicators including atmospheric concentrations of greenhouse gases, sea level rise, and sea ice extent. The year 2016 was the hottest year on record, with many weather and climate extremes, according to the most recent WMO report.^[10]

As of August 2020, the WMO has a membership of 193 member states and territories.^[11]

• Disaster risk reduction
• The Global Framework for Climate Services (GFCS)
• The WMO Integrated Global Observing System (WIGOS)
• Aviation meteorological services
• Polar and high mountain regions
• Capacity development
• Governance

In keeping with its mandate to promote the standardization of meteorological observations, the WMO maintains numerous code forms for the representation and exchange of meteorological, oceanographical, and hydrological data. The traditional code forms, such as SYNOP, CLIMAT and TEMP, are character-based and their coding is position-based. Newer WMO code forms are designed for portability, extensibility and universality. These are BUFR, CREX, and, for gridded geo-positioned data, GRIB.^{[citation needed]}

In 2007, the Intergovernmental Panel on Climate Change (IPCC), a joint creation of the WMO and the United Nations Environment Programme (UNEP), received the Nobel Peace Prize "for their efforts to build up and disseminate greater knowledge about anthropogenic (man-made) climate change, and to lay the foundations for the measures that are needed to counteract such change."^[12]

The World Meteorological Day is held annually on 23 March.^[13]

WMO states that "the International System of Units (SI) should be used as the system of units for the evaluation of meteorological elements included in reports for international exchange."^[14] The following units, which include units which are not SI units, are recommended by the WMO for meteorological observations:

• Degrees Celsius (°C) for temperature, or alternatively Kelvin (K).
• Metres per second (m/s) for wind speed.
• Degrees clockwise from north (°) for wind direction, or alternatively on the scale 0-36, where 36 is the wind directly from north and 09 is the directly wind from east.
• Hectopascals (hPa) for atmospheric pressure.
• Percent (%) for relative humidity.
• Millimetres (mm) for precipitation (or the equivalent unit kilograms per square metre (kg/m²))
• Millimetres (mm) for evaporation.
• Millimetres per hour (mm/h) for precipitation intensity, or alternatively kilograms per square metre per second (kg/m²/s)
• Hours (h) for sunshine duration.
• Metres (m) for visibility.
• Metres (m) for cloud height.
• Standard geopotential metre (m') for geopotential height.
• Kilograms per square metre (kg/m²) for snow water equivalent.
• Watts per square metre (W/m²) for irradiance.
• Joules per square metre (J/m²) for radiant exposure.
• Oktas for cloud cover.

• The World Meteorological Organization at a Glance
• WMO Public website
• WMO for Youth
• WMO Bulletin (twice annually)
• WMO Greenhouse Gas Bulletin (annually)
• WMO Statements on the Status of the World Climate (annually)
• In September 2020 the WMO published a high-level brief compilation of the latest climate science information from the WMO, GCP, UNESCO-IOC, IPCC, UNEP and the Met Office. The United in Science 2020 Report is subdivided into 7 chapters, which each have a list of key messages.^[15][16]

• International Meteorological Organization Prize^[17]
• Professor Dr Vilho Väisälä Awards^[18]
• Norbert Gerbier-Mumm International Award (suspended in 2014)^[19]
• WMO Research Award for Young Scientists^[20]
• Professor Mariolopoulus Award^[21]

As of May 2019, WMO Members include a total of 187 Member States and 6 Member Territories.^[22]

Ten United Nations member states are not members of WMO: Equatorial Guinea, Grenada, Liechtenstein, Marshall Islands, Palau, Saint Kitts and Nevis, Saint Vincent and the Grenadines and San Marino. Cook Islands and Niue are WMO Members but non-members of the United Nations. Vatican City and State of Palestine and the states with limited recognition are not members of either organization.

The six WMO Member Territories are the British Caribbean Territories (joint meteorological organization and membership),^[22] French Polynesia, Hong Kong, Macau, Curaçao and Sint Maarten (joint meteorological service and membership)^[22] and New Caledonia. (List of all members with admission dates.)

Membership by regional associationsEdit

Region I (Africa)Edit

Region I consists of the states of Africa and a few former colonial powers. Region I has 57 member states and no member territories:^[23]

Non-member

• Equatorial Guinea

Region II (Asia)Edit

Region II has 33 member states and 2 member territories. The member states are:^[25]

The member territories are:

• Hong Kong
• Macau

Region III (South America)Edit

Region III consists of the states of South America, including France as French Guiana is an overseas region of France. It has a total of 13 member states and no member territories:^[26]

Region IV (North America, Central America and the Caribbean)Edit

Region IV consists of the states of North America, Central America, and the Caribbean, including three European states with dependencies within the region. It has a total of 25 member states and 2 member territories. The member states are:^[27]

Region V (South-West Pacific)Edit

Region V consists of 23 member states and 2 member territories. The member states are:^[28]

Region VI (Europe)Edit

Region VI consists consist of all the states in Europe as well as some Western Asia. It has 50 member states:^[29]

States with membership in more than one regionEdit

A total of ten member states have membership in more than one region. Two nations are members to four different regions, while eight are members of two regions. These nations, with their regions, are as follows:

• Aircraft Meteorological Data Relay (AMDAR)
• Cloud atlas
• Global Atmospheric Research Program (GARP)
• Global Climate Observing System
• International Cloud Atlas
• Regional Specialized Meteorological Centre

• "Public website". WMO.
• "Severe World Weather website". WMO.{{cite web}}: CS1 maint: url-status (link)
• Official website   (as of October 2018, this functions as a WMO Extranet for the WMO Community as an interim solution until a new WMO Community website can be launched)
• "International List of Selected, Supplementary and Auxiliary Ships". International Comprehensive Ocean-Atmosphere Data Set (ICOADS). 1999. Pub 47. Including country codes
• "World Climate Conference-3 (WCC-3)". WMO. August 2009.{{cite web}}: CS1 maint: url-status (link)