Aim: Safe driving is influenced by various factors, including the driver's level of cognitive performance and thermal comfort. The aim of this study was to investigate temperature indicators, thermal comfort, and mental function parameters among taxi drivers in winter. Methods: This cross-sectional study was performed on 30 taxi drivers in the morning and evening (8–9AM, 4–6PM). In this study, temperature parameters, including dry-bulb temperature and relative humidity, thermal comfort indices, demographic parameters and cognitive performance parameters, including accuracy, work speed, attention, number of errors, mental fatigue, concentration skills, and auditory short-term memory, were measured. Statistical analyzes were performed using SPSS version 26. Results: The average dry-bulb temperature and relative humidity inside the cabin in the morning and evening were 23.2%, 22.1%, 22.3%, and 21.3%, respectively. The results showed that the drivers' dissatisfaction with the temperature in the morning and evening shifts was 6% and 5.6%, respectively. There was no statistically significant difference in the measured parameters in the morning and evening shifts (P > 0.05). The results showed that there was a significant relationship between age and some cognitive function parameters (P < 0.05). Conclusion: More than 90% of drivers feel comfortable when the average dry bulb temperature of 22%–23% can be used to adjust the optimal temperature of the cabin vehicle in winter. Age is an effective factor in the cognitive performance of drivers and the cognitive performance of the drivers was not in a favorable condition, which requires further study to investigate the causes of this issue.