Temperature in a continuous steel annealing furnace is studied using a 3D finite element model with minimal simplification of the furnace design and heat transfer physics. This allows investigation of the temperature distribution of the furnace and steel strip and provides understanding of important operational factors such as increased heating of the strip edges and cooling of thermocouple probes due to radiative heat transfer. This information enables the use of simpler models in production situations and can help optimize furnace operating methods and improve product quality.