Climate change in the region in terms of changes in temperatures may seriously affect snow melting rates in the watershed and hence flows at dam. The main source of flows is snowmelt and rainfall that varies with temporal and spatial scale. So, understanding of spatial and temporal variability of climatic parameters is most important for the management of water resources. The present study was conducted to test the existence of monotonic trends and relative change (step change) in the annual and seasonal regional maximum, minimum, and mean and diurnal temperature data produced by thiessen polygon method from a meteorological network of stations in Mangla watershed for the period 1971-2010. Significant trends were detected by applying the student t test, Mann Whitney U, Spearman and Mann Kendall tests in time series of temperature for Mangla catchment and its sub-basins (Kanshi, Poonch, Kunhar and Neelum). The results of this study revealed that Climate change is occurring more severe with warming trends in lower part of Mangla catchment whereas cooling trends were in higher part. The prevailing trends, caused by climate change, have an effect on the flows that should be considered by the water managers for better water management in a water scarcity country like Pakistan.