This paper presents a numerical simulation of a pine tree thermal response and the thermal radiative phenomenon, in order to evaluate the forest fire sustainability. The three-dimensional pine tree model is made by 2289 cylindrical elements, with 1.8 m height, to represent its trunk, branches and leaves. The tree thermal response numerical models are based on energy and mass balance integral equations. The tree systems consider the phenomena of conduction, convection, transpiration and radiation. The tree is placed nearby the fire front. The view factors, Mean Radiant Temperature, surface temperature of both bodies are analyzed on transient regime. In accordance with the obtained results in trees, with lower dimensions, is important not to expose during long time to the radiative phenomenon and after a short time period the steady state regime is obtained.