Can higher incomes reduce economic and social damages from higher temperatures? Causal investigation of this question has been challenging because income differences correlate with cumulative exposure and either may drive observed differences in the deleterious effects of heat. We revisit the same-day temperature–violence relationship in Mexico and show that a conditional cash transfer program attenuated the effects of higher temperatures on violent behavior, but only temporarily. Within five years of receiving ongoing monthly transfers, the heat-violence relationship returns to pre-program levels even as transfers continue. Our results highlight potential limitations of higher incomes in adaptation to rising temperatures.