Climates fluctuate all the time – over seasons and years. Winters change to spring. Some summers are warmer than others. Scientists determine average climate from a calculation of conditions over a 30-year period. These averages create a baseline for comparing the current weather and climate. It helps answer questions like, “Are we having a hotter month, season or year than average?”

In a narrow sense, climate is the average weather condition in an area over a long period of time. In a broader sense, climate is the status of the climate system that comprises the atmosphere, the hydrosphere, the cryosphere, the surface lithosphere and the biosphere. These elements all determine the state and dynamics of the Earth’s climate. 

The process of computing long-range predictions – climate outlooks ranging from 30 days up to two years – on the global scale requires huge amounts of computer power along with a very specialized knowledge so there are only a few centres – known as Global Producing Centres for Long-Range Forecasts (GPCs)  – that produce these. The services they provide set the context essential for predicting climate and weather on regional scales by both Regional Climate Centres (RCCs) and Regional Climate Outlook Forums (RCOFs) and on local scales National Meteorological and Hydrological Services.

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Particularly Vulnerable Areas

Vulnerability Climate Map

Long-term observing stations

Long-term meteorological observations are a valuable part of the cultural and scientific heritage of mankind as they are unique sources of past information about atmospheric parameters as references for climate variability and change assessment. To highlight this importance, WMO created a mechanism for recognizing long-term observing stations. The mechanism is intended to promote sustainable observational standards and best practices which facilitate the generation of high-quality time series data in the future.

Regional Climate Outlook Forums

Regional Climate Outlook Forums (RCOFs) produce consensus-based, user-relevant climate outlook products in real time through regional cooperation and partnership in order to reduce climate-related risks and support sustainable development for the coming season in sectors of critical socioeconomic significance for the region in question.


The Secretary-General and other WMO officials participate in sessions of the Conference of the Parties (COP) of the United Nations Framework Convention on Climate Change (UNFCCC) each year to provide the latest scientific advice and information to governments.