Although meteorology probably has a greater influence on marine and air navigation than any other individual science, many users are not fully aware of the problems of present-day forecasting, nor do they make full use of the services available. This paper is intended to give some idea of the value of observers' reports, the importance of communications, and the problems of present-day forecasting. In particular, attention is drawn to the rapid increase in upper air soundings and the interdependence of surface and upper air observations in predicting the elements for all marine and aeronautical services. Arising from the application of upper air data to surface forecasting, the paper emphasizes the value of applying comprehensive analyses and of marine forecasts prepared by weather centrals ashore; in areas where facilities are not available to the marine user, however, knowledge and experience of single-observer forecasting are still needed.