Beef cattle change their voluntary feed intake (VFI) levels with changes in environmental variables such as temperature, humidity, wind speed and precipitation. Confined beef cattle producers can adjust ration formulation to maximize production under these varying conditions. Therefore, it is important for producers to accurately estimate the changes in VFI in order to maintain maximum production efficiency. This study focuses on the indirect effects of precipitation and temperature on VFI during the winter months. The National Research Council (1981) suggests 5 to 30 percent reductions in VFI with feedlot mud depths of 5 to 60 cm. The goal of this study is to develop a simple model to calculate feedlot mud depth and to present the results in a manner that will be easily interpretable by producers. As an example, the depth of mud in Oklahoma for the winter of 2001-2002 is calculated. The model generated may then be combined with the effects of other environmental variables during all seasons to create a more complete, year-round model for prediction of VFI.