  In the last decade, wildfires have become wider and more destructive. The
climate change and the growth of urban areas may further increase the
probability of incidence of large-scale fires. The risk of fire can be lowered
with preventive measures. Among them, firefighting lines are used to stop the
fire from spreading beyond them. Due to high costs of installation and
maintenance, their placement must be carefully planned. In this work, we
address the wildfire management problem from a theoretical point of view and
define a risk function to model the fire diffusion phenomena. The land is
modeled by a mixed graph in which vertices are areas subject to fire with a
certain probability while edges model the probability of fire spreading from
one area to another. To reduce the risk, we introduce the {\sc Windy Firebreak
Location} problem that addresses the optimal positioning of firefighting lines
under budget constraints. We study the complexity of the problem and prove its
hardness even when the graph is planar, bipartite, with maximum degree four and
the propagation probabilities are equal to one. We also show an efficient
polynomial time algorithm for particular instances on trees.
