This study aims to examine the influence of seasonal variations of thermal variables on comfort temperature in schools in a warm and humid climate. Schoolchildren in Nigeria are engaged in in-class lessons in the two seasons experienced in the country. There have been concerns about whether seasonal variation in thermal variables can affect the thermal comfort of building occupants. To address this issue, data were collected from 180 healthy primary schoolchildren aged 7 - 12 years old. The research methodology consisted of measuring environmental variables, while questionnaires were applied to the children during the rainy season and dry season. The result shows some significant seasonal differences in the measured thermal variables and comfort temperature. The mean indoor temperature observed during the dry season was 29.1?C while during the rainy season the mean value was 28.1?C. The subjects found the indoor environment acceptable during the rainy season, while during the dry season it was found unacceptable. Furthermore, differences in neutral temperature and comfort range between seasons were observed. Architects and facility managers need to have information about thermal conditions in schools according to season. This is because primary schoolchildren are vulnerable, and exposing them to variations in indoor temperature may impact on their health and academic performance.