Summary:

The aim of the study was the characteristics of thermal-precipitation conditions in the Opole voivodeship on the basis of mean monthly air temperature, and precipitation values from the 1981-2010 period from the Łosiów, Stare Olesno, Opole, and Głubczyce weather stations. Basic statistical characteristics of the thermal-precipitation conditions were calculated. They were mean monthly, and annual air temperature, and precipitation values over the 30-year period, standard temperature deviations, and precipitation variability coefficients. It was also studied whether there were trends of change as far as temperature, and precipitation were concerned. In addition, the dates of the beginning, and end of thermal periods, as well as their lengths were determined. The determined periods were: thermal winter, the economic period, vegetation period, intense vegetation period, and ripening period, corresponding to the period of thermal summer. During the last stage of study, dryness indicator A was calculated. On the basis of the calculations carried out, it was stated, that in the Opole voivodship the mean annual air temperature ranged from 8.0ºC, and 9.1ºC, and in the case of two towns it increased significantly. A significant increase in monthly temperature was also observed in April, and in the summer months. The increase in temperature translated into changes in the length of thermal periods, which, in the studied area, differed in length. Winter lasted from 54 to 78 days, the economic period from 246 to 260 days, vegetation period from 221 to 235 days, intense vegetation period from 161 to 176 days, and the summer period from 90 to 111 days. Annual precipitation means ranged from 586 mm in Głubczyce, to 652 mm in Stare Olesno, and were characterized by variability: from 17 to 21%. Significant increasing trends were stated in annual precipitation totals in Łosiów, and Głubczyce, and in monthly precipitation totals, above all in January, February, November, and July. The changes in thermal, and precipitation conditions translated into the changes in the dryness indicator values. From June to August, an increase in the value of the indicator was stated, and in January - a decrease, which means that there is an increasing threat of drought in the summer months, whereas January is more, and more humid.