Wildfire is capable of rapidly releasing the energy stored in forests, with the amount of water in live and dead biomass acting as a regulator on the amount and rate of energy release. Here we used temperature and fuel moisture data to examine climate-driven changes in fuel moisture content over the past three decades. We then calculated the changes in energy release (energy release component and fire radiant energy) for two forests that experienced drought and bark beetle mortality and were subsequently burned by wildfires. We found that mortality transitioned substantial amounts of biomass from live to dead pools. Coupled with climate-driven decreases in fuel moisture content, this change in fuel availability increased the amount of energy that could be released as heat during wildfire in these forests. Our results demonstrate that climate-driven tree mortality and fuel aridity may be increasing the amount of energy that is released during wildfire.