Surface main meteorological stations are stations with 2 to 5 professional observers and enclosed premises (usually a detached building), which perform observations or register all meteorological variables 24 hours a day in accordance with the regulations of the World Meteorological Organisation and the National Meteorological and Hydrological Service.
Data are forwarded via meteorological messages to the WMO global telecommunication system.

Most stations are equipped with automatic weather stations measuring one or more meteorological variables 24 hours a day and are part of the MHS information system. These stations undergo operative data processing, completeness control, consistency control and space control. All data, including automatic station data, are stored in computer processing media. User programmes make possible the delivery of data for various purposes. Station spatial distribution is satisfactory and meets WMO requirements. Station altitude distribution should be improved.