In this work we propose the use of a cellular automata defined on unstructured triangular grids to simulate forest fire propagation. This approach allows us to model computational domains with complex geometries (a domain bounded by a polygonal). It still retains the easy implementation of cellular automata and does not present the anisotropy induced by regular grids. The forest fire spread is modeled by using ignition and burning probabilities for three different fuels. Each cell assumes four states: nonflammable cell, fuel cell, burning cell and burned cell. Ignition probability is modified by effects of type of fuel, ambient temperature/relative humidity slope and wind (intensity/direction). Numerical simulations reproduce the qualitative behavior of forest fires
