Abstract
The air temperatures recorded at Warsaw-Okęcie in 1951-2010 were compared with forecasts for the period 1980-2010 and 1991-2010, i.e. 31 and 20 years ahead. Accurate predictions of air temperatures in Warsaw in 1980-2010 were calculated using the cycles identified by applying the sinusoidal regression method to a series of monitoring results obtained in Warsaw between 1779 and 1979. The high accuracy of these forecasts is the result of a similar progression of measured and forecast values over a number of years. The prediction of climate change in the Northern Hemisphere for example, caused by interference of long solar radiation cycles as well as variations in the concentrations of the δ18O oxygen isotope in the Arctic ice cores, requires a larger series of data points.