Field measurement of fine fuels' moisture content and its relation to meteorology and wildfire activity in the Central Region of Portugal (2000-2024)

Dead fuel moisture content (DFMC) has historically been a key indicator of fire danger, while live fuel moisture content (LFMC) still plays a limited role in most operational systems. Direct comparative analyses remain scarce in Mediterranean regions, with implications for fire danger assessment and fire behaviour modelling. This study analyses 25 years (2000-2024) of fuel moisture content measurements, collected under consistent field and laboratory procedures, for surface litter and live shrubs from typical species in Central Region of Portugal. We analysed how both DFMC and LFMC are associated with wildfire activity (overall and large events) during the most critical fire season (June-September), using Spearman correlation. Indices from the Canadian Fire Weather Index System (CFWIS) are used as a reference framework for interpreting the results. The Central Region of Portugal provides relevant context for this assessment, as it lies in one of the country's most fire-prone areas. Results for overall wildfire activity showed slightly stronger correlations for LFMC with both the number of fires and burned area than DFMC, with relationships improving when data were aggregated into 10-day periods. For large events, meaningful associations emerged only at the annual scale, where LFMC displayed significant negative correlations, highlighting the potential of shrub species to indicate seasonal conditions favourable to large wildfire development. These results were consistent with the patterns observed in the CFWIS indices with respect to wildfire activity across different scales. This study recommends the implementation of similar long-term datasets and identifies many directions for further research. • DFMC correlates strongly with FFMC and FWI; shrub LFMC aligns best with DC. • Shrub LFMC shows slightly stronger correlations to NF and BA than DFMC. • Ten-day periods improve FMC-fire activity relationships, especially for LFMC. • Shrub LFMC shows significant annual correlations with large fire activity. • FWI system indices show correlation patterns consistent with FMC-fire activity.