During 2000 and 2010, air conditioning was not allowed during the entrance exam sessions even when average temperature reached 30°C in Taiwan. This thesis explores the temperature effects on students’ performances by using universal Taiwanese test scores data of college/university entrance exams and hourly weather condition data at county level. OLS models are constructed controlling for weather conditions other than temperature, high school fixed effects and year fixed effects, in the hope that the change in students’ test scores brought by temperature can be more accurately estimated. As the temperature rises by 1°C, significant drops are found in test scores of art/social science subjects, which are Chinese, English, History, Math B and Geography. However, the temperature effects on scientific subjects are not significant. The result implies that the ban of air conditioning during test sessions makes the entrance exam an inefficient tool in measuring students’ true abilities. In addition, the result suggests that the loss in working productivity brought by 1°C in temperature is significant.