This chapter describes how meteorology information is entered into the program using a Meteorologic Model. The Meteorologic Model is responsible for preparing the boundary conditions that act on the watershed during a simulation. Consequently, a Meteorologic Model is prepared for use with one or more Basin Models. If the Basin Model contains subbasin elements, then the Meteorologic Model must specify how precipitation will be generated for each subbasin (only when using non-gridded methods). Evapotranspiration should be included if the Basin Model is configured for continuous simulation using any of the following loss methods: Deficit Constant, Gridded Deficit Constant, Soil Moisture Accounting, Gridded Soil Moisture Accounting.