Power devices in the wind turbine power converter system suffer from two-scale thermal loadings, the fundamental frequency thermal cycling and low frequency thermal cycling and these thermal loadings introduce different consumed lifetimes. Furthermore, the fluctuation of ambient temperature influences the thermal loadings. Therefore, accurate lifetime estimation should consider the ambient temperature. However, previous studies limited by the calculation of junction temperature only consider the mission profile of wind speed but not ambient temperature. This paper adopts the Bayerer lifetime model to evaluate the effect of ambient temperature on the consumed lifetime of power semiconductors based on a numerical junction temperature calculation method considering the actual ambient temperature and wind speed of Lauswiesen and Valkenburg in 2015. Studies show that long-term fluctuation of ambient temperature increases the consumed lifetime of device, and the fluctuation of ambient temperature mainly influences the consumed lifetime due to low frequency thermal cycling, but have little effect on the consumed lifetime due to fundamental frequency thermal cycling.