This study investigates the impact of the expected climate changes in the Apulia region (Southern Italy) for the next 100 years on the climatic water balance variations, climatic classifications and crop water requirements. The overall results indicated that an increase of temperature, in the range between 1.3 and 2.5 degrees C, is expected in the next 100 years. The reference evapotranspiration (ETo) variations would follow a similar trend; as averaged over the whole region, the ETo increase would be about 15.4%. The precipitation should not change significantly on yearly basis, although, a slight decrease in summer months and a slight increase during the winter season are foreseen. The climatic water deficit (CWD) is largely caused by ETo increase, and it would increase over the whole Apulia region in average for more than 200 mm. According to Thornthwaite and Mather climate classification (1957), the moisture index will decrease in the future, with decrease of humid areas and increase of aridity zones. The net irrigation requirements (NIR), calculated for ten major crops in the Apulia region, would increase significantly in the future. By the end of the 21(st) Century, the foreseen increase of NIR, in respect to actual situation, is the greatest for olive tree (65%), wheat (61%), grapevine (49%), and citrus (48%) and it is slightly lower for maize (35%), sorghum (34%), sunflower (33%), tomato (31%), and winter and spring sugar beet (both 27%).