Technical Abstract: Weather data are critical information for strategic natural resource and environmental planning because weather directly influences virtually all natural phenomena. Unfortunately, historical records for situations and locations of interest are often either unavailable or of insufficient duration to provide adequate information. Consequently, mathematical weather simulation models are commonly used to generate synthetic weather records for use in the study and management of natural resources. Most weather generators are capable of producing one or more components of weather such as precipitation, temperature, solar radiation, humidity and wind speed with the same statistical characteristics as naturally occur for a given location. Because of the importance of weather influences on agricultural and natural resource management, two USDA agencies - the Agricultural Research Service (ARS) and the Natural Resources Conservation Service (NRCS) - formed a collaborative weather simulation team. The USDA weather generator research and development effort is led by scientists from NRCS and ARS locations around the country. The purpose of the team is to develop an improved weather simulation tool for use in natural resource management projects and studies involving, for example, the impacts of management alternatives and climate change on agricultural production, natural vegetation dynamics, water quality, and watershed hydrology.