A composite index is proposed for fire destruction danger assessment. Wildfire incidence and fire severity (FS), in association with the values in threat and the sensitivity of these values to fire, are some of its constituent parameters. The index is computed by use of logic programming within a multi-criteria Decision Support System (DSS). It is applicable to either large or small areas and can be used for short and long-term prediction. The Decision Support System is also described along with the underlying reasoning assumptions. It incorporates mechanisms for the representation and handling of uncertainty and can reason with inexact or incomplete information. The building blocks of its architecture consist of hierarchically-structured rules, a scheme that offers a high degree of transparency. The system design provides a high degree of flexibility, and allows user-induced customisation. It can be used either as stand-alone or as a component of an integral software system, as it is a Fire and Forest Management Decision Support System, by the use of an appropriate interface.