Global warming has great influences on crop yields. However, several researchers have concluded that global warming has taken a “hiatus” in recent years. Here, we hope to identify the temperature trends of the winter wheat growing seasons and quantitatively estimate the effects of temperature variations on wheat yields. We carry out trend analysis on daily maximum (Tmax) and minimum temperatures (Tmin) from 1980 to 2014 in Jiangsu Province of China. The results indicate there are increasing trends for both Tmax and Tmin during 35 years, but no significant trends in the years after 2000. In addition, the increasing rates of the Tmin are larger than those of Tmax over the 35 years within all stations and all growing stages, which suggests that winter wheat is exposed to asymmetrical warming. The results of correlation analysis and regression analysis reveal that increases in Tmin have significant adverse effects on wheat yields.