The indice forêt météo (IFM) is an estimation of the risk of wildfire computed by Météo France, the French national meteorology institute; it means Forest weather index. It was created in 1992 and is based on a Canadian empirical model developed in 1976. The index is a whole number that ranges between 0 and 20, 20 being the maximum risk. it is computed from: This index is computed for 40 zones of France, three are in the Landes (département with the biggest forest of France). The computed index is revised every year to take new data into account.