In the Mediterranean climate zone, characterized by the Csa climate type, people's thermal comfort conditions deteriorate due to heat stress. This study focuses on determining the thermal comfort conditions of seasonal agricultural workers during the hot periods of the year when agricultural production is intense in developing Türkiye, located in the Mediterranean climate zone, where agricultural production cannot yet be carried out with high technology, and developing suggestions that can guide the authorities in this context. In this study, the thermal comfort conditions of seasonal agricultural workers working in agricultural lands in Csa were determined using the modified Physiological Equivalent Temperature (mPET) index in the Rayman model, according to their activity energy during intensive and less intensive agricultural work. These conditions were evaluated for ten-day, monthly, and seasonal periods. As a result of the research, it was observed that there were differences in the thermal comfort conditions of seasonal agricultural workers according to time and activity energy. It has been observed that agricultural workers, especially those working in soil cultivation (intensive activity), have a higher mPET value between 2.1°C and 2.9°C than agricultural workers engaged in plant care and harvesting (less intense activity). It has been determined that the thermal comfort conditions of agricultural workers engaged in plant care and harvesting deteriorate between 09.00 and 15.00, and for agricultural workers engaged in soil cultivation, between 08.00 and 16.00. According to the results, suggestions were developed within legal limits for the regulation of the working systems of agricultural workers.