Components of a quantitative risk assessment were produced by simulation of burn probabilities and fire behavior variation for 134 fire planning units (FPUs) across the continental U.S. The system uses fire growth simulation of ignitions modeled from relationships between large fire occurrence and the fire danger index Energy Release Component (ERC). Simulations of 10,000-50,000 years were performed using artificial weather sequences generated by time-series analysis of recorded ERC values at local weather stations. Also needed were monthly distributions of wind speed and direction, as well as spatial data on fuel and topography. Fire suppression was represented by a model of the probability of fire containment by suppression forces, based on fire growth rates, days since ignition, and fuel type. Simulated values of burn probability generally fell within a factor of three of observed values. At the pixel level, burn probabilities vary markedly based on differences in fuels, weather, and topography. The slope of the frequency-magnitude distribution of simulated fire sizes was compared to historic records in each region, demonstrating that the model produced fire size distributions similar to historic patterns. Because model parameters included only a limited suite of weather, fuel, and suppression variables, this result is interpreted to mean that observed fire size distributions are a function of the joint distributions of spatial opportunities for fires to grow to different sizes (dependent on fuels and ignition location) and temporal variability in the length of weather sequences conducive to fire growth. A contribution of this research is the practical aspect of performing fire simulations at national scales for operational planning and ecological research.