Tourism ecological capacity assessment is an estimate of the capabilities and limitations of land for tourism development, which determines and grades the environmental capacity for the establishment of infrastructure and recreational activities by measuring the ecological characteristics of the land. On the other hand, tourists tend to settle in a place that has the highest degree of comfort and favorable climatic conditions. Therefore, assessing the ecological capacity of tourism and determining the number of months that are favorable for the presence of tourists in the region is of great importance. Accordingly, the present study assessed the climate of comfort and ecological capacity for the development of sustainable tourism in Khuzestan Province. According to the results obtained, the ecological capacity for development in Khuzestan Province is equivalent to 13457.18 km², with a significant portion of these areas located in the southwestern regions of the province. Moreover, this province has 57101.28 km2 of ecological capacity for the development of extensive tourism. As the results showed, the best time for tourism in the province is autumn and winter (November to March), and night comfort in most areas is more desirable than during the day, and cities such as Dezful, Gotvand, and Shushtar have night comfort for up to 12 months. Additionally, Dehdez was recognized as the best tourist destination in all seasons, with 12 months of comfort, according to the TCI index. Accordingly, according to the results of the ecological capacity and climate comfort obtained from the Khuzestan Province, it is possible to allocate appropriate tourism infrastructure and develop recreational activities commensurate with the capacity of region, providing a logical relationship and sustainable compatibility between the natural capacity of the environment and the needs of tourists.