During a ski touring outing, practitioners evolve in an uncertain environment which is subject to snow avalanches. To make this evolution as serene as possible, the choice of the itinerary is of upmost importance and must be based on an aggregation of several heterogeneous criteria. The paper proposes a fuzzy rule-based system for aggregating criteria evaluations. Such fuzzy rule-based system produces results that are then rendered in a numerical virtual model using a 3D visual application. The aim of this application is to assist the ski tourer for itinerary decision making thanks to a visual rendering of the snow avalanche risk.