The U.S. Forest Service produced this map showing wildfire potential in the lower 48 states. Higher resolution versions are available.
Here is how the USFS describes this map:
“The wildland fire potential (WFP) map is a raster geospatial product produced by the USDA Forest Service, Fire Modeling Institute that is intended to be used in analyses of wildfire risk or hazardous fuels prioritization at large landscapes (100s of square miles) up through regional or national scales. The WFP map builds upon, and integrates, estimates of burn probability (BP) and conditional probabilities of fire intensity levels (FILs) generated for the national interagency Fire Program Analysis system (FPA) using a simulation modeling system called the Large Fire Simulator (FSim; Finney et al. 2011).
The specific objective of the 2012 WFP map is to depict the relative potential for wildfire that would be difficult for suppression resources to contain, based on past fire occurrence, 2008 fuels data from LANDFIRE, and 2012 estimates of wildfire likelihood and intensity from FSim. Areas with higher WFP values, therefore, represent fuels with a higher probability of experiencing high-intensity fire with torching, crowning, and other forms of extreme fire behavior under conducive weather conditions.
Using the FPA FSim products as inputs, as well as spatial data for vegetation and fuels characteristics from LANDFIRE and point locations of fire occurrence from FPA (ca. 1992 – 2010), we used a logical series of geospatial processing steps to produce an index of WFP for all of the conterminous United States at 270 meter resolution.”