The work was based on results of research on husked oats, Jawor c.v., conducted in 1992-2003 at three stations of cultivar assessment located at Ruska Wieś, Seroczyn and Lulbliniec Nowy. The experiment was set up on three soils of rye complex. The date of development stages occurrence was registered during oats vegetation. Grain yield and its usable traits, i.e. 1000 grain weight, husk content and offal, were assessed after harvest. Average air temperature, rainfall total and number of days with rainfall per individual development stages were calculated basing on daily measurements of average air temperature and precipitation total. In order to determine the relationships between the investigated variables, simple correlation and segment regression were used. The length of development stages was correlated to a greater degree with average air temperature for individual development stage than with the date of individual stage occurrence. Low values of simple correlation coefficients between the length of development stages and the date of their occurrence and oat grain yield and its usable traits (1000 grain yield, contents of husk and offal) were found. Analysis of segment regression (linear segments) allowed to increase the efficiency of predicting independent variables. In the case of oat grain yield the dependent variables included: length of periods, shooting-panicle appearance, panicle appearance-wax maturity, wax maturity-full maturity and the length of total growing period. The length of sowing-harvest period may provide efficient information about husk and offal content, whereas the length of tillering-shooting period or date of panicle appearance may provide information about the 1000 grain weight.