This paper presents the basic features of annual course of air temperatures and the sum of precipitation (diversification of temperatures and precipitation in separate months and seasons). The paper also determines air temperature and precipitation fluctuations in 1861-2007 and the trends of changes. Finally, the relations between the North Atlantic Oscillation (NAO) and the air temperatures and precipitation sums are established.
A method of forecasting rainfall and mean temperature is presented. It is based on plant phenology and probability distribution of both random variables. This method makes it possible to give a forecast for each recorded phenological stage; the time horizon of the longest of them exceeds 90 to 100 days. A verification test based on data from different regions of Poland proved the method to be very efficient comparing to prediction using simple climate averages. It was applied to a case of 1982 and potato phenology, as an example.