Site-specific soil moisture information is important for a variety of forest ecological issues, forest assessments and decisions based on them. With global warming and the increased occurrence of periods of drought and heavy precipitation events, the demand for such spatially and temporally highresolution information is increasing. Existing systems such as the UFZ drought monitor or the DWD’s map of Germany for soil moisture meet requirements to a limited extent only, as the relationship between the effects to forest stands is inadequate. In forest ecology research and forest environmental monitoring, process-oriented and site-specific water balance models for evaluating the water balance have been established for a long time. So far, these models have been used successfully in retrospective case studies or for scenario analyzes. Application in real time and thus the full exploitation of the potential of such deterministic models has been restricted through technical limitations and insufficient data sets for parameterization. These deficits have now been remedied with the “Soil Moisture Traffic Light”. In our article we present this prototype of a web-based information system for the daily assessment of the water availability of forest stands. We describe the technical components, the parameterization of the continuously working water balance model LWFBrook90R as well as the graphical result presentation, which is offered in a simple and an expert mode. An outlook is given on potential technical developments.