Across five studies, the authors demonstrate that warm (vs. cool) temperatures deplete resources, increase System 1 processing, and influence performance on complex choice tasks. Real-world lottery data (pilot study) and a lab experiment (Study 1) demonstrate the effect of temperature on complex choices: People are less likely to make difficult gambles in warmer temperatures. Study 2 implicates resource depletion as the underlying process; warm temperatures lower cognitive performance for nondepleted people but do not affect the performance of depleted people. Study 3 illustrates the moderating role of task complexity to show that warm temperatures are depleting and decrease willingness to make a difficult product choice. Study 4 juxtaposes the effects of depletion and temperature to reveal that warm temperatures hamper performance on complex tasks because of the participants’ increased reliance on System 1 (heuristic) processing.