This work uses the results of Post-registration Cultivar and Agricultural Experimentation conducted in 2003–2011 in Lower Silesia, on soils of very good and good wheat complex as well as very good rye complex. Regression models were created for crude fat and total protein contents in the seed of oilseed rape. The following factors were included: the average air temperature and total precipitation in the periods: September-November (from sowing to end of vegetation in the autumn), December-March (stopped vegetation – renewal of vegetation), April (renewal of vegetation –beginning of flowering), May (flowering), June (end of flowering – technical maturity), the content of phosphorus, potassium and pH of soil, and fertilisation with nitrogen, phosphorus and potassium. The models show that the meteorological conditions from December to March and in May have the strongest influence on the content of crude fat and total protein in seeds of oilseed rape. Optimal for fat content is high rainfall in the periods of December-March, April and May, and the accompanying higher temperatures. In these periods a higher protein content is obtained in lower rainfall and lower temperature conditions. In the period from the end of flowering to technical maturity, the highest fat content is noted at relatively low rainfall – 25 mm and a higher temperature of 18.8°C. In this period the protein content is influenced only by the temperature, in this case, negatively.