We estimate the supply-side effects of climate change on firm sales by exploiting variation in local average temperature across suppliers of the same client. A 1°C increase in temperature leads to a 2.5% decline in annual sales. This effect is nonlinear, with stronger effects among suppliers in regions with the largest temperature increases and in cooler regions. Manufacturing and heat-sensitive industries are more affected, consistent with a reduction in labor productivity and labor supply when local temperatures rise. Nondiversified and financially constrained firms are also more affected, supporting the importance of operational and financial flexibility in adapting to climate change.