The ASNE MSEA office is working on developing an air and space environmental infrastructure to support DoD M&S programs. Historically, there has been very little weather play in simulations and it has been too expensive or too hard to retrofit legacy M&S systems with a weather-play capability. This is about to change; the new DoD M&S programs like the Joint Simulation System (JSIMS), the Joint Warfare System (JWARS), and the Joint Modeling and Simulation System (JMASS) will be interactive with the air, space, oceans, and terrain (physical and manmade structures) natural environment and take into account the effects of the natural environment on simulation objects. The ASNE MSEA (along with the Oceans MSEA and Terrain MSEA) have a number of projects in work to ensure that the natural environment data provider community has the wherewithal to support these simulation programs. We anticipate that both the private and other government sectors will increasingly be using M&S as a basis for analyzing courses-of-action and equipment acquisition as well as for training, etc.