The main purpose of this paper is to present a fire behaviour system, developed to estimate fire progression, smoke dispersion and visibility impairment, at a local scale, and to evaluate its performance by comparing results with measurements from the Gestosa 2004 experimental field fires. The system is an improvement of two already available numerical tools, DISPERFIRE (Miranda et al. 1994) and FireStation (Lopes et al. 2002), which were integrated. FireStation is a software system aimed at the simulation of fire spread over complex topography. DISPERFIRE is a real-time system developed to simulate the dispersion in the atmosphere of the pollutants emitted during a forest fire. In addition, a model for the estimation of visibility impairment, based on the relationship between air pollutants concentration and visibility, was included in DISPERFIRE. The whole system was developed using a graphical interface, previously created for FireStation, which provides user-friendliness and easily readable output to facilitate its application under operational conditions. The system was applied to an experimental field fire and the main results were compared with experimental air pollutant concentration measured values. The performance of the model in predicting pollutant concentrations was good, particularly for NO₂ and PM₁₀.