The variability of the mean annual air temperature and precipitation totals in three periods: 1848–2010, 1951–2010 and 1981–2010 was investigated in the large Warta River basin, being the area with lowest rainfall in Poland. For the purposes of research, nine meteorological stations with the longest measurement series were selected. Air temperature increase in this river basin was similar than in neighbouring countries. In the last 30 years this trend kept increasing. The precipitation in the whole studied period was slightly increasing in the northern part of the Warta River basin, but decreasing in the southern part. The mean annual precipitation totals in the catchment area did not change visible. In the period 1981–2010, the precipitation totals show a small increase in the winter and spring and a decrease in summer. A negative influence of this climate change was not visible in the Warta River discharge. The main objectives of this study were the collection long-term records of air temperature and precipitation in the Warta River basin, and the statistical analysis of climate variability.