We estimate the impacts of temperature on alleged and substantiated child maltreatment among young children using administrative data from state child protective service agencies. Leveraging short-term weather variation, we find increases in maltreatment of young children during hot periods. We rule out that our results are solely due to changes in reporting. Additional analysis identifies neglect as the temperature-sensitive maltreatment type, and we do not find evidence that adaptation via air conditioning mitigates this relationship. Given that climate change will increase exposure to extreme temperatures, our findings speak to additional costs of climate change among the most vulnerable.