Labor productivity, human capital formation, and income growth decline amid hot ambient temperatures. The implications of such temperature sensitivity for climate change damages depend upon the capacity for human adaptation to persistent temperature changes—as opposed to idiosyncratic temperature variation. Studying millions of collegiate track and field performances from 2005 to 2019, this paper shows that performance diminution in hot ambient conditions is mitigated by heat adaptation, a physiological response to heat stress and associated physical and cognitive impairments. Across varied specifications of the temperature-performance relationship, adaptation reduces performance losses from alternative climate change scenarios by more than 50%.