In Phase I of this NASA SBIR project, Daniel H. Wagner Associates, Inc., designed and demonstrated the feasibility of a system for integrating environmental data into flight planning and execution for Unmanned Air Systems (UAS) in the National Airspace System (NAS). The Weather Aware Route Planning (WARP) system will provide weather-based Indicators and Warnings (I&W) and navigational recommendations for UAS in order to improve their autonomy, safety, and energy efficiency. Using all available environmental and navigational data, WARP will assess environmental impacts to planned/executing flight plans and generate alerts and recommendations for those plans based on expected environmental impacts. Operating in conjunction with existing and emerging mission planners and ground control systems (GCS), WARP will use a combination of rules-based/heuristic and simulation-based approaches to assess environmental impacts to UAS flight plans and provide I&W and recommendations for each UAS to avoid negative environmental impacts and take advantage of positive environmental impacts. WARP will also provide real-time environmental impact assessments during mission execution, assisting ground-based pilots, and eventually UAS autonomous controllers, in performing dynamic re-planning for safer and more efficient flight.