Sexual conflict can lead to adaptations that increase male reproductive success at the expense of harming females (‘male harm’) and decreasing population growth. Studying the ecology of male harm is paramount to understanding how sexual conflict unfolds in nature and its consequences for population viability. We used seed beetles (Callosobruchus maculatus), a species where males harm females through harassment and traumatic insemination, to examine whether temperature (24ºC, 28ºC, 32ºC) modulates pre-copulatory harm (harassment) or pre- and post-copulatory harm (harassment and mating) in females exposed to low or high sexual conflict (one or two males, respectively), vs. once-mated females (no harm). Constant exposure to males decreased female fitness at warmer environments, particularly at 28ºC, and when females were subject to constant harassment and mating under high sexual conflict. In contrast, constant exposure to male harassment and mating increased female fitness at 24ºC, particularly under low sexual conflict (significant ~14% increase vs. control females). At the population level, under no harm female net reproductive rate was higher at 28ºC and 32ºC, but reversal of the cost/benefit balance of exposure to males resulted in optimal net reproductive rates at 24ºC under constant male-female cohabitation, hence rescuing population growth rate. Our findings show that, by dictating the outcome of female fitness under constant male exposure, temperature can modulate sexual conflict to the point of reversing it and facilitating evolutionary rescue. Our results support the notion that environmental variation decrease overall levels of sexual conflict in nature.