This paper examines the impact of temperature variability on bank systemic risk and the mediating effect of natural disasters. By employing data of 105 Chinese city commercial banks and 30 provinces from 2008 to 2020, we find a positive relationship between temperature variability and bank systemic risk, as well as the mediating effect of natural disasters. Moreover, heterogeneity analysis demonstrates that the relationship between temperature variability and bank systemic risk is only significant for banks in regions with small seasonal temperature differences and southern provinces of China.