My research explored how rising temperatures associated with climate change affect reptiles, focusing on the impacts of heatwaves on adult male fertility and the effects of differences in developmental temperatures on post-hatching traits in an Australian lizard. I found that heatwaves reduced male fertility, with additional negative effects with increased heatwave intensity. I also found that variation in developmental temperature had short- and long-term effects on lizard growth, behaviour, and physiology, which, in some cases, differed between males and females. Taken together, my research provides evidence for significant impacts of climate warming on lizards, both through reproduction and developmental environments.