Nature has been adversely affected by increasing industrialization -especially after the latter half of the last century when accelerating technological development, unplanned urbanization, incorrect agricultural policies, deforestation, and the excessive and unsuitable use of energy have acted as factors to increase the release of gases into the environment. The global warming effect of greenhouse gases has had a negative impact on the meteorological and hydro-meteorological parameters, such as the temperature and precipitation, which are the main elements of a region's climate. In particular, sudden changes occurring in air temperature lead to major changes in the design of air conditioning systems, energy analysis, and heating-and cooling-load calculations such as degree-day. Various energyforecasting methods are being developed for air-conditioning systems in buildings, animal shelters and controlled environmental agriculture structures. Accurate and easily accessible climatic data are extremely important in terms of analysing the accuracy and energy efficiency of air conditioning systems. In this study, the trends and changes over a long period of daily maximum, minimum and mean temperature data were analyzed using the Mann-Kendall trend test and linear regression analysis, and comments have been made about nine provinces in the Southeastern Anatolia Region of Turkey. As a result of these analyses, it has been concluded that maximum temperatures of the provinces of Adiyaman, Gaziantep, Mardin, Sanliurfa, the mean temperatures of the provinces of Adiyaman, Batman, Gaziantep, Kilis, Mardin, Siirt, Sanliurfa and Sirnak, and the minimum temperatures in the provinces of Gaziantep, Kilis show statistically significant rising trends.