World Weather Watch

Collecting, exchanging, processing and providing climate and hydrological observations, forecasts and data exchange to all WMO programmes.

Two men standing in front of a painting of a rocket.

The World Weather Watch (WWW) is one of the crowning achievements of WMO. The celerity with which WMO responded to the introduction of meteorological satellites with the establishment of the World Weather Watch, and its subsequent adoption by all WMO Members, set a standard for international cooperation in operational programmes that remains unequalled today

In its first decades, WMO observed considerable progress in many countries in expanding and improving both observational and telecommunications capabilities. Networks of land stations increased while merchant shipping and special ocean weather vessels continued to play an important role over the seas, complemented in some areas by meteorological ocean buoys. In addition, civil aviation started to provide valuable upper-air information along major flight routes. But large areas over which little meteorological information was available remained. A major breakthrough – meteorological satellites – partially filled these gaps. On 4 October 1957, the Union of Soviet Socialist Republics (USSR) launched the first Earth-orbiting satellite SPUTNIK-1, followed later in the same year by SPUTNIK-2 and the EXPLORER-1 satellite launched by the United States of America (USA) on 2 January 1958. The world’s first dedicated weather satellite, the Television Infrared Observation Satellite (TIROS-1), was launched by the US on 1 April 1960. These launches effectively marked the beginning of a new era of observational data coverage for the whole globe and were key triggers for one of the most significant developments in the history of meteorology: the inception of the WMO World Weather Watch Programme.

The World Weather Watch is a resounding success by any metric, both in terms of meeting its primary goal of enabling the weather services around the world to better serve their users and in terms of providing a model for successful international collaboration on a global scale. Over this half-century, weather prediction information and products have gone from being of interest mainly to the shipping and aviation communities and a few hobbyists to being considered vital for the protection of life and property and for routine operations and decisions affecting nearly every sector of the global economy. The fact that almost every sector of the economy now depends on weather forecast information is a feather in the cap of WMO, the WWW and the National Meteorological and Hydrological Services, but it also brings with it enormous responsibility.

It is worth remembering that no nation, however wealthy and powerful, can serve its citizens with the kind of timely and reliable weather information they have come to expect and depend on without the collaboration of all others as exemplified by the World Weather Watch. It is important that the World Weather Watch continues to evolve and grow. 


The World Weather Watch (WWW) Programme facilitates the development, operation and enhancement of worldwide systems for observing and exchanging meteorological and related observations. It also generates and disseminates analyses and forecast products, as well as severe weather advisories and warnings, and related operational information. The activities carried out under this Programme ensure that Members have access to the required information that enables them to provide data, prediction and information services and products to users. The World Weather Watch is organized as an international cooperative programme, under which the infrastructure, systems and facilities needed for the provision of these services are owned, implemented and operated by Member States and Territories.


The collection, exchange and processing of weather, climate and hydrological observations are essential for:

  • determining the current state of the atmosphere;
  • weather forecasting, including severe weather forecasting and warning services;
  • monitoring climate variability and climate change;
  • climate prediction; and
  • underpinning the work of the Global Framework for Climate Services.

The World Weather Watch has evolved to take advantage of technological advancements in observing systems, for example in remote sensing, communications systems such as coordinated private Internet type networks, and faster and more powerful super computing systems for data analysis and the running of dynamic weather, climate and environmental prediction models.  Such advanced technology is essential for improving the technical systems of the Programme and calls for special efforts in the provision of technical guidance, specialized training and capacity development.


The Commission for Basic Systems takes a leading role in the technical development and implementation of the Global Observing System (GOS), together with the Commission for Instruments and Methods of Observation, other technical commissions, regional associations, and relevant international organizations and programmes, . As the key component of the WMO Integrated Global Observing System (WIGOS), it meets the requirements of all WMO and co-sponsored Programmes. Commission for Basic Systems also leads the technical implementation and operation of the WMO Information System (WIS), including the Global Telecommunication System (GTS) its core network. The Commission similarly leads the enhancement and implementation of the Global Data-processing and Forecasting System, which provides increased lead-time and reliability of forecasts and warnings and is critical in supporting the delivery of services to both the public and the private sector.


The three core elements of the World Weather Watch are the Global Observing System (GOS), the Global Telecommunications System (GTS) and the Global Data-processing and Forecasting System (GDPFS). Several support programmes coordinate, integrate and operate the three core components under the governance and management of the relevant Technical Commissions.

Emergency Response Activities (ERA)

The Emergency Response Activities (ERA) Programme involves the application of specialized atmospheric dispersion-modelling techniques to track and predict the spread of airborne hazardous substances in the event of an environmental emergency. This kind of specialized application depends directly on the operational infrastructure of the numerical weather prediction systems that are implemented and maintained at many of the global, regional or national meteorological centres within the WMO World Weather Watch system. The Programme was established to assist National Meteorological and Hydrological Services (NMHSs), their respective national agencies and relevant international organizations, to respond effectively to environmental emergencies involving large-scale dispersion of air-borne hazardous substances.

Global Observing System (GOS)

The WMO operates a coordinated system of methods and facilities for making meteorological and other environmental observations on a global scale in support of all WMO programmes. The system, called the Global Observing System (GOS), is comprised of operationally reliable surface-based and space-based subsystems. The GOS is comprised of observing facilities on land, at sea, in the air and in outer space.  These facilities are owned and operated by the Member countries of WMO who strive to meet responsibilities in the agreed global scheme so that all can benefit from their consolidated efforts.

Global Telecommunications System (GTS)

The WMO Global Telecommunication System (GTS) is the communications and data management component that allows the World Weather Watch (WWW) to operate through the collection and distribution of information critical to its processes. It is implemented and operated by National Meteorological Services of WMO Members and International Organizations, such as ECMWF and EUMETSAT. As decided by Congress and the Executive Council, the GTS also provides telecommunication support to other WMO programmes, facilitating the flow of data and processed products to meet requirements in a timely, reliable and cost-effective way, ensuring that all Members have access to all meteorological and related data, forecasts and alerts. This secured communication network enables real-time exchange of information critical for forecasting and warnings of hydrometeorological hazards in accordance with approved procedures.

The Instruments and Methods of Observation programme (IMOP)

The Instruments and Methods of Observation Programme (IMOP) supports the improvement of the quality and long-term stability of observations and measurements of meteorologi­cal and related environmental variables. This is achieved through standardization activities and coordination and promotion of the use of effi­cient methods and technology to meet the requirements of operational and research applica­tions. The Programme also enhances the effective and economic use of observing technology/systems through training and technology transfer in developing countries. IMOP develops technical standards and guidance material, and conducts relevant studies on instruments and methods of observations.

WMO Information System

The WMO Information System ensures the extension of the WMO policy on the free and unrestricted international exchange of meteorological and related data and products. Thanks to WMO, the data and derived products are available and exchanged freely and in an unrestricted manner every day between WMO centres and weather offices in each country. They are provided quickly and efficiently, using the latest information and communication technologies.

Global Data-processing and Forecasting System

The Global Data-processing and Forecasting System (GDPFS) represents the function of weather forecasting including the production of weather and climate analyses, forecasts, specialized forecast products, and alerts, advisories and warnings of severe weather for the protection of life and property. The GDPFS includes the network of operational meteorological centres that produce a wide range of numerical weather prediction (NWP) products, forecasts, and warnings, and is a part of a global early warning system for meteorological and environmental hazards.


An image of a spacecraft flying over a white background.

Early on the United Nations (UN) acknowledged the dangers as well as the benefits of more and more nations launching satellites. It recognized the fact that WMO provided a potential model for open and friendly cooperation on space matters between nations, for mutual and worldwide benefit. Accordingly, one of the first resolutions approved by the UN for “international cooperation in the peaceful uses of outer space” laid down heavy demands upon WMO. Resolution No. 1721 (XVI), adopted unanimously by the UN General Assembly on 20 December 1961 stated:

“The General Assembly, Noting with gratification the marked progress for meteorological science and technology opened up by the advances in outer space, Convinced of the world-wide benefits to be derived from international co-operation in weather research and analysis,

Recommends to all Member States and to the World Meteorological Organization and other appropriate specialized agencies the early and comprehensive study, in the light of developments in outer space, of measures; (a) To advance the state of atmospheric science and technology so as to provide greater knowledge of basic physical forces affecting climate and the possibility of large-scale weather modification;(b) To develop existing weather forecasting capabilities and to help Member States make effective use of such capabilities through regional meteorological centres;
Requests the World Meteorological Organization, consulting as appropriate with the United Nations Educational, Scientific and Cultural Organization and other specialized agencies and governmental and non-governmental organizations, such as the International Council of Scientific Unions, to submit a report to the Governments of its Member States and to the Economic and Social Council at its thirty-fourth session regarding appropriate organizational and financial arrangements to achieve those ends, with a view to their further consideration by the General Assembly at its seventeenth session...”
WMO promptly reacted with its “First Report on the Advancement of Atmospheric Sciences and their Application in the light of Developments in Outer Space.” The term World Weather Watch (WWW) was introduced by one of the writers, Dr Wexler (USA), and the overall objective was described by another writer, Academician Bugaev (USSR), as “to develop WWW in such a way as to ensure that any country could receive meteorological information on any scale.” The report discussed a wide range of subjects including weather forecasting and climatology and their applications, the possibility of changes in the global climate, weather modification and the meteorological aspects of water resources. However, most of the emphasis was placed on what could be considered operational service aspects: observational data and the associated telecommunication system to permit rapid collection and dissemination of data and products. Accordingly three areas in which substantial progress was considered to be essential for the WWW were identified: (a) global observational data coverage, (b) data processing systems and (c) a worldwide coordinated telecommunication system.

The First Report undoubtedly ranks as one of the most significant documents in the history of WMO. It was submitted to the fourteenth session of the WMO Executive Council in 1962 and subsequently provided to the UN General Assembly and other bodies. At the 17th UN General Assembly in December 1962 the report was very favourably received and a new resolution (Resolution 1802 (XVII)) was adopted as a sequel to the previous one. The Fourth World Meteorological Congress (April 1963) considered the two UN resolutions, accepted the responsibilities placed upon WMO by those resolutions and decided to: (a) approve WWW as an extension of long-established plans for facilities and services required by the meteorological services; (b) establish a Development Fund in support of WWW; and (c) establish a WWW planning unit in the Secretariat.

A man kneeling in front of a large metal sphere.

Implementation and definition of components
Between the Fourth (1963) and Fifth (1967) World Meteorological Congresses, considerable progress was made in the planning of the WWW and WMO Members began to adapt their Meteorological Services to fit in with this new structure. The Fifth Congress also adopted the first WWW Plan and Implementation Programme for the period 1968-1971. This Programme outlines the general features of the structure of the WWW as a dynamic, evolutionary system with worldwide ramifications.

From the outset, the WWW included three major components, namely the Global Observing System (GOS), the Global Data-processing and Forecasting System (GDPFS), and the Global Telecommunication System (GTS). It was organized in a three-tier structure consisting of the World Meteorological Centres (WMCs), Regional/Specialized Meteorological Centres (RSMCs) and National Meteorological Centres (NMCs). Since its establishment in 1963, the WWW has developed essentially as an aggregation and coordination of all the facilities controlled by the Meteorological Services of Members. The establishment and successful operation of the WWW were crucially important for a significant improvement of weather forecasts and climate records.

In 1984, two additional elements were added to the WWW Plan, namely, the Monitoring and Operational Information Service and the WWW Implementation Support. As experience accumulated with monitoring and operating the WWW, the final structure underwent slight modifications. Currently, the WWW comprises the design, implementation, operation and further development of the following three core components:

The GOS, consisting of facilities and arrangements for making observations at stations on land and at sea, and from aircraft, environmental satellites and other platforms;
The GTS, consisting of integrated networks of telecommunications facilities and services for the rapid, reliable collection and distribution of observational data and processed information;
The GDPFS, consisting of World, Regional/Specialized and National Meteorological Centres in order to provide processed data, analyses, and forecast products.

The coordination, integration and operation of these three components are achieved through two support programmes, the WWW Data Management programme and the WWW System Support Activity programme. In addition, the WWW Programme incorporates four programmes that complement and enhance the core components of the WWW and provide significant input and support to other WMO Programmes: (a) the Instruments and Methods of Observation Programme; (b) the Tropical Cyclone Programme; (c) the Emergency Response Activities; and (d) the WMO Antarctic Activities programme.