The Integrated Terminal Weather System (ITWS) is one of two major development projects sponsored by the FMs Aviation Weather Development Program. Focused on the environment within the airport terminal area, ITWS integrates data from FAA and National Weather Service (NWS) sensors and systems to provide a suite of weather informational products for improving air terminal planning, capacity, and safety. This article provides an overview of the ITWS project, presenting the system concept, some of the design and engineering challenges, and plans for development that will lead to operational systems in the field.