Predicting responses of intertidal species to changes in ocean and air temperatures requires an understanding of how thermal stress alters organismal physiology and energy budgets. Intertidal organisms are unique in experiencing two distinct thermal environments daily, with the oscillation of tides, and it is not clear whether changes in air and water temperature influence intertidal species in similar ways. We used a Scope for Growth (SFG) framework to quantify the effects of warming air and water temperatures for a population of the intertidal barnacle Balanus glandula from Friday Harbor, WA. B. glandula is a sessile crustacean common to the upper intertidal of the northeastern Pacific, from Alaska to Mexico. We developed the SFG model from a field study of barnacle growth in combination with laboratory measurements of the effect of temperature on B. glandula’s feeding rate, aquatic respiration, aerial respiration, and recovery from aerial exposure. We estimated energy intake from the relationship between tissue growth and estimated temperature and size-dependent feeding and costs. Net energy balance was not significantly greater than zero for adult B. glandula in both the upper and mid intertidal. Simulated increased air temperatures caused the energy balance to decrease, while increased water temperature increased the energy balance. Our results suggest that, at least in the northern part of its range, B. glandula’s growth is limited by cold water temperatures, and that even modest ocean warming could ameliorate the negative effects of increasing body temperatures at low tide.