Convective instability can influence the behaviour of large wildfires. Because wildfires modify the temperature and moisture of air in their plumes, instability calculations using ambient conditions may not accurately represent convective potential for some fire plumes. This study used the North American Regional Reanalysis to develop a climatology of the convective environment specifically tied to large fire events. The climatology is based on the period 1979-2009 and includes ambient convective available potential energy (CAPE) as well as values when surface air is warmed by 0.5, 1.0 or 2.0 K or moistened by 0.5, 1.0 or 2.0 g kg-1. Results for the 2.0 K and 2.0 g kg-1 modifications are presented. The results reveal spatial and seasonal patterns of convective sensitivity to added heat or moisture. The patterns suggest that use of ambient CAPE to estimate the potential plume growth of a large wildfire may underestimate that potential in heat- or moisture-sensitive regions.