The effect of the variation of climatic input parameters on the leaching of pesticides is presented in this study. Based on weather series with daily precipitation and temperature data over a period of 30 years for a total of 13 regions in Germany Monte-Carlo simulations using the computer model PELMO have been performed for spring as well as for autumn applications. The results show that independent on the region the fluctuations always decreased with increasing leaching potential. The geometric standard deviation for pesticide concentrations of 1.0 mu g/l was in the range of 1.6 to 2.4. However, simulations with an example pesticide demonstrated that the differences between different regions were of higher importance than differences due to variance of climate within a given region. It was concluded that the next generation of our information infrastructures needs to take into account the spatial component of input data.