Official reports indicate that the number of forest fires and areas affected by fire in Serbia is increasing. Changes in temperature and precipitation, important factors in fire behaviour, were determined by comparison between the standard climatological period (1961-1990) and the period 1981-2010. The study processed and compared the data from 26 meteorological stations on the territory of Serbia. In order to determine the risk of fires, values of the Lang precipitation factor and Ångström index are calculated. It is found that the mean values of temperature significantly increased during the second period at all stations in Serbia. The small values of the precipitation factor are recorded during summer, but also in the spring months. Research has shown that an increase in air temperature and reduction of precipitation in the examined period has a great influence of the possibility of fire occurrence. It is concluded that there is a higher fire danger risk during the summer months in Serbia. It is found that eastern and southern Serbia are particularly vulnerable to forest fires because of small values of the Lang precipitation factors.