Abstract: Understanding the dryness and drought phenomena is fundamental in explaining the landscape features and the rational use of water resources in a region. The authors aim to assess the climatic water deficit (WD) in one of the most sensitive regions in Romania in terms of aridity: Southern Oltenia. Defining and characterizing the intense aridity was done based on the Thornthwaite method under a multi-annual regime (1961-2007) and during the growing season (April-October) in order to reveal the climate suitability for human activity and the optimum conditions for the main crops. In southern Oltenia the Thornthwaite aridity index values (Iar-TH) (%) defines an arid area, increasing from north to south and south-west from 40-45% to 50%. The highest values displaying a pronounced aridity (Iar-TH ≥ 50%) cover a significant part of the Blahniţa Plain, Desnăţui Plain, Southern Romanaţi Plain (Dăbuleni Field), the Jiu Valley and the entire Danube Plain (about 65% of the entire surface).