The analysis of the triggering thresholds is aimed at answering the question of when an event can take place. Based on the historical information on rainfall—the main triggering factor of this type of landslides—the triggering thresholds of debris flows have been investigated with the aim to provide additional elements to the knowledge of the critical rainfall. Nevertheless, the most directly factor related to the triggering of debris flows is the soil moisture level that depends not only on the intensity of rainfall in a given moment, but also by the thermoprecipitation regime of the previous period. The state of soil saturation was analysed in this study in laboratory with the pressure plate extractors techniques and monitored in field by the FDR probes. The responses of the FDR probes seem to confirm the data modelling, showing in some cases a marked sensitivity to the rainfall input. Coupling rainfall and soil water content data, the study would give a contribution to the development of more effective early warning systems. . © Springer International Publishing Switzerland 2015.