Comparison of fire danger indices in the Mediterranean for present day conditions

This paper assesses the ability of two forest fire danger indices to estimate fire danger and to define the beginning and the end of fire season. Two indices are studied: the Canadian Fire Weather Index (FWI) and the Finnish Forest Fire Index (FFI). The indices are designed to meet the needs of particular regions but they have also proved to be suitable for the Mediterranean region. The aim of this study is to assess the skill performance of both indices and identify their strengths and weaknesses. The Canadian FWI depends on temperature, precipitation, relative humidity and wind measurements, while the Finnish FFI relies on potential evaporation and precipitation. Results indicate that, in general, FWI and FFI determine a fairly similar fire danger for a set of weather conditions. Higher correlations are found especially for locations under significant fire danger. The results improve for the lower values of fire danger if a spin up period is used in the computation of FFI. Both indices show similar features especially during summer, but some deviations are typical during early spring and autumn, as FWI probably overestimates the fire danger.