The relevance of water vapour for the radiative budget of the atmosphere as well as aerosol growth, cloud formation and weather forecasting contrasts strongly with the availability of humidity data in the Arctic. Acting as the most important greenhouse gas, the water vapour distribution influences the ground temperatures, while especially in the Arctic the surface temperature feeds strongly back by expansion or shrinking of permanently frozen ground and sea ice extension. About 80 radiosonde stations are located north of 60°N, launching in most cases between one and two sondes per day. Up to now this irregular distributed humidity data set is the most extensive, but the reliability of this humidity measurements under Arctic conditions is still under discussion. Additional information like e.g. radiometer data is sparse. An increasing number of ground-based GPS receivers complements the database, providing integrated water vapour (IWV) information, if meteorological ground data is available. An evaluation of IWV data from ground-based GPS even under the low humidity condition of the Arctic will be presented. The possibility of the retrieval of IWV data from GPS soundings combined with meteorological data from radiosondes or numerical models will be discussed.