The identification of the relationships between fire severities and fire types can be a new way to obtain knowledge about variables that cause transitions between surface and crown fires. In this study, we analyze the variables that influence fire severity and their relationship to
changes in fire type in a wind-driven wildfire that burned under extreme conditions in the Northeast Iberian Peninsula. Ten of the 12 variables that affected severity were related to fuels, 1 was topographic, and 1 was related to fire spread. Not all changes in fire severity imply changes
in fire type. Changes in green and scorched severities were not related to changes in fire type, but there was a strong relationship between changes in scorched and charred severities and the transition to active crown fires. The wind alignment and percentage of large trees contributed to
the transition to charred severity and to the initiation of an active crown fire, whereas the cessation of an active crown fire and the transition to scorched severities were affected by tree density and the type of slope. The use of this methodology in other wildfires could provide a better
understanding of the variables that influence the transitions to crown fires.