The term heat island describes built up areas that are hotter than nearby rural areas. The annual mean air temperature of a city with 1 million people or more can be 1.8-5.4 degrees F (1-3 degrees C) warmer than its surroundings. In the evening, the difference can be as high as 22 degrees F (12 degrees C). Heat islands can affect communities by increasing summertime peak energy demand, air conditioning costs, air pollution and greenhouse gas emissions, heat-related illness and mortality, and water quality (EPA, 2013). Urban heat islands are one of the most important problems of cities today and are experienced in Turkey similar to other cities in the world due to the spatial increase in urbanisation. It is known that the existence of green spaces has an important role in decreasing the negative effects of urban heat islands. The objective of this study is to determine the cooling effect of the Ataturk Forest Natural Park, which is 26.6 ha located in the city centre. Within this scope, mobile temperature values were taken at 41 points, 250 m apart, within the Ataturk Forest Natural Park and its surroundings. The result of the geostatistical analysis shows a temperature difference of up to 5.5 degrees C between the Ataturk Forest National Park and its surroundings. This difference can be effective over an approximately 400 m radius.