Trend analyses of rainfall and temperature extremes are of great importance to understand the process underlying climate change in Palestine. In this study, a trend analysis of long-term rainfall and temperature data for Nablus Meteorological Station (NMS) was carried out. Based on the available data, the fundamental statistical concepts and trend analysis were employed to characterize rainfall and temperature data series for the period from 1975 to 2015. In the analysis of rainfall, it was proved that rainfall of NMS is of high variability where the annual rainfall approximately varies between 335 and 1,400 mm with an average of 654 mm. The overall trend of rainfall is towards a wetter climate, with an estimated increase of about 18 mm in the entire studied period. Similarly, two period averaging 600 mm and 690 mm respectively were detected from fluctuation in rainfall. The trend of the first period (1975-1991) is towards a drier climate, whereas the trend of the second period (1992-2015) is towards a wetter climate. In the analysis of temperature, the temperature variability among years was proved, with a standard deviation of 0.7 ^oC and average of 18.4 ^oC. The annual mean temperature changes of NMS are characterized by a warming trend. Since 1975, there has been an increase in the annual mean temperature of about 0.92 ^oC/40 years (≈ 0.023 ^oC/year). Additionally, the use of cumulative deviations detected two main periods in the temperature of Nablus city. A relatively cool period from 1975 until 1992 has been followed by the warm period on record from 1997 to present. It was concluded that the changes in climate of NMS are considerable and can affect the sustainable development if mitigation measures does not implies.