The need for climatological data of the North Sea has increased during the past years. The increase in offshore and recreational activities can benefit greatly from such data. In order to meet this need weather observations made by ships and lightvessels in the North Sea have been processed extensively, which has resulted in a large number of tables, charts, etc. with climatological data. This publication gives a selection of these data, in which the emphasis lies on wind and wave data. In addition, some characteristic data on air and sea tempera ture, cloud cover, precipitation, visibility...