The environment dramatically influences phenotypic variation either by acting as a selective force on existing phenotypes, or via phenotypic plasticity. Plastic responses to the environment can be observed across traits, taxa, and life stages, but developmental stages are particularly sensitive to environmental influence. Furthermore, plastic responses during these stages can interact and carry fitness consequences into later life stages. Developmental plasticity can lead to significant variation in phenotypes, the causes and consequences of which are poorly understood, especially across entire lifespans. The brown anole (Anolis sagrei) has well-documented plastic responses to components of the developmental environment, such as temperature, which can affect incubation duration, survival, and other fitness-related traits. However, many studies use few treatment groups and lack the capacity to provide well defined reaction norms. To determine the effects of incubation temperature across life stages, we incubated brown anole eggs under eight constant temperatures and conducted a field-based mark-recapture study on the resulting hatchlings. We generated high-resolution reaction norms for several phenotypic traits, and found that there was variation in thermal response curves with respect to egg hatching success and phenology of hatching. Although high temperatures were thermally stressful to embryos, they also reduced incubation duration and led to earlier hatching. In turn, earlier hatching increased the probability of survival to adulthood. Consequently, the optimal incubation temperature differs among life stages. This study emphasizes the complexity of plastic responses during development and their potential effects on fitness across the lifespan.