Introduction and purpose: Thermal comfort conditions are a set of thermal conditions that can be appropriate for at least 80% of people. The absence of thermal comfort conditions is considered as a bipolar phenomenon of cold to warm or hot discomfort, which creates different levels of thermal stress. In this comparative study, we analyzed the temporal and spatial distributions of thermal stresses on the north and south coasts of Iran with a focus on health and tourism. Methods: In the present study, we used the daily data of temperature, wind speed, relative humidity, and cloud cover from 2000 to 2014. First, the mean radiant temperature (TMRT) parameter was calculated in the RayMan software program, and then the universal thermal climate index (UTCI) values were extracted from 16 selected stations on the north and south coasts using the Bioclima software. Results: During the warm period, the most severe thermal stresses occurred on the south coast, especially on islands, but on the north coast, only cold stresses were recorded that were not of high severity. The most severe hot and cold stresses were calculated for Abu Musa Island and Siah Bishe, respectively. Conclusion: There are several levels of thermal stress on the north and south coasts of Iran. This issue is more intense for the southern coast due to severe thermal stresses over a long period of time. The importance of thermal stresses in the concepts of health and tourism requires researchers to pay attention to the related climatic parameters and tensions.