In an approach to explain why snow loads on roofs increase when an early melting period occurs, the increased snow load is seen as condensation of humidity of the air onto snow covered roofs. 2-D simulations were performed with the Fluent model. The humidity of the air is considered as small droplets. The condensation rate is 3-5 kg/m2 h. The simulations show that the wind side of the roof is more subjected to condensation than the lee side. This study indicates that short-term condensation onto snow covered surfaces should be paid more attention.