Fire season precipitation variability influences fire extent and severity in a large southwestern wilderness area, United States

Despite a widely noted increase in the severity of recent western wildfires, this trend has never been quantified. A twenty-year series of Landsat TM satellite imagery for all forest fires on the 1.4 million ha Gila National Forest suggests that an increases in area burned and area burned severely from 1984-2004 are well correlated with timing and intensity of rain events during the fire season. Winter precipitation was marginally correlated with burn severity, but only in high-elevation forest types. These results suggest the importance of within-season precipitation over snow pack in modulating recent wildfire size and severity in mid-elevation southwestern forests.