The burning index of the National Fire Danger Rating System is designed to measure potential fire workload over broad geographic areas that can be represented as being homogeneous with respect to fuel, topographic, and weather conditions. The utility of this index is confirmed by its relation to three measures of fire workload--number of fires, area burned, and number of personnel used in fire suppression-- for National Forests in southern California. The distributions of these measures over 15 years were skewed heavily to the right ('heavy-tailed distributions'). We selected the 75th, 90th, and 95th percentile values of each distribution at ten percentile values of the burning index to investigate and display the association between fire workload and the burning index. The results provide a distinct view of the direct relationship between wildfire workload and critical burning index values for the southern California area as a whole, and point to the potential value of this approach for anticipating fire control problems in other areas. © IAWF. Reproduced from the International Journal of Wildland Fire (Mees, R. and R. Chase, 1991) with the kind permission of CSIRO PUBLISHING on behalf of the International Association of Wildland Fire. (http://www.publish.csiro.au/journals/ijwf/).