Lightning activity is the main natural reason to start forest fires. An ignition during lightning activity is caused by cloud-to-ground lightning discharge. Initiation of the forest fire ignition determines by chemical and physical processes during discharge influence. There are differences in electric current conduction within a tree trunk for coniferous and deciduous species. The main part of fire incidents occurs in the coniferous forest stands. It is necessary to simulate tree ignition by the cloud-to-ground lightning discharge. The simple heat transfer mathematical model is used to simulate coniferous tree ignition. Probabilistic criterion is used to assess forest fire danger level caused by lightning activity and forest conditions. In general, forest fire danger depends on lightning activity, meteorological conditions and vegetation on the forested territory. Meteorological parameters like environmental temperature are used in the mathematical model of tree ignition. Tree breed is taking into account using tree trunk structure and thermophysical parameters of coniferous wood. Also model uses electric current parameters of the cloud-to-lightning discharge. In principle, a mathematical model may take into account multi-stroke of the lightning discharge. It is suggested to use a specific geoinformation system developed for forest fire danger assessment. Using of the ArcGIS or QGIS software is not suitable for realization of the program instruments of tree ignition and probabilistic estimation. It is suggested to use high-level programming language for program realization of the mathematical models of forest fire initiation during lightning activity. Dialog mode is used in developed software to organize the interaction with users. The Origin Pro Software is used to visualize prognostic information on forest fire danger levels. Contours options can be used to map lightning activity, forest conditions and forest fire danger level using probabilistic estimation. The Origin Pro Software is applied in conjunction of the executable files of developed software to simulate forest fire danger. This software package can be used in forestry to implement decision-making function during fire season.