This work presents a study of the possibility of estimating forest fire danger by means of the analysis of the temporal evolution of the Normalized Difference Vegetation Index (NDVI) Advanced Very High Resolution Radiometer (AVHRR). Images of Spain corresponding to areas of Valencia and Eastern Andalusia in 1993 have been used. The slope of the evolution curve of the NDVI is an indicator of water stress and it is used to estimate danger. Forested areas are previously selected using the NDVI integral in the period studied. In order to determine the reliability of the index, ground data measured by the Spanish National Forestry Service (ICONA) are available to us