The present study is carried out to find out the long-period variation of seasonal temperature of the districts Bankura and Purulia of West Bengal located on Lower Gangetic Basin. Temperature is a prime element which determines the Climate of the districts Bankura and Purulia. In this study, temperature has been analyzed statistically to determine the variability in magnitude over the period 1901-2000. The temperature data of the districts Bankura and Purulia have been collected from the India Meteorological Department (IMD), Pune. Trends are analyzed using Mann-Kendall test for the data period 1901-2000. From the trend analysis we observed that seasonal temperature variation of summer of the district Bankura is decreasing trend and the district Purulia is increasing trend. The fluctuation of Monsoonal and post Monsoonal temperature of both districts are decreasing trend but variation of winter temperature of both districts are increasing trend. For all cases the value of Mann-Kendall Z are greater than 1.64 at 0.05level. So, all results are statistically significant.