Nisava River is the largest tributary of the South Morava River of length 248 km, of which 151 km is in Serbia. Annually to all three hydrological profiles (Pirot, Bela Palanka and Nis) in the reporting period (1961-2000) has been observed decrease in discharge. That would be in accordance with the IPCC's claims about the domination of the influence of anthropogenic greenhouse gases on the reduction of rainfall and discharge in Serbia. However, the area of the Nisava basin in the second half of the XX century has shown decrease in air temperature. The station Dimitrovgrad, in the upper part of the basin, from 1949 to 2007 showed trend of annual temperature of -0.0049ºC per year, which does not fit to the concept of dominance of anthropogenic greenhouse gases. And the trend of rainfall in this period, changes sign from negative to positive (0.1175mm per year), so that it does not fit the concept of domination of the global anthropogenic impact on regional models of IPCC. Regarding to this and projections of possible climate change in the future all potential climatic factors should be taking into account.