[The influence of climatic condition on behavior is especially important in the study of primate mother-infant interactions, because thermoregulatory requirements may influence contact between individuals. However, weather conditions are not often considered in the interpretation of data. This study examined the relationship between ambient temperature and the behavior of 135 captive mother-infant baboon pairs living in outdoor social groups. We analyzed several measures of contact (ventroventral contact, making and breaking contact, contact index), mother-infant interactions, and general activity. A total of 7230 fifteen-minute observations were collected during the first 8 weeks of the infants' lives, during which temperatures ranged from -2.2 to 41.1°C (average 23.3°C). Partial correlations between temperature and the mean frequency or duration per hour of each behavior category, while controlling for the effect of infant age, indicated that temperature had a significant overall effect on several behaviors related to contact and proximity. Ventroventral contact and huddling the infant were significantly negatively related to temperature, while the frequency of making and breaking contact with the infant were positively related to temperature. In addition, temperature was related to other behaviors at particular weeks of infant age. This study indicates that temperature should be considered as an important variable in understanding nonhuman primate mother-infant behavior., The influence of climatic condition on behavior is especially important in the study of primate mother-infant interactions, because thermoregulatory requirements may influence contact between individuals. However, weather conditions are not often considered in the interpretation of data. This study examined the relationship between ambient temperature and the behavior of 135 captive mother-infant baboon pairs living in outdoor social groups. We analyzed several measures of contact (ventroventral contact, making and breaking contact, contact index), mother-infant interactions, and general activity. A total of 7230 fifteen-minute observations were collected during the first 8 weeks of the infants' lives, during which temperatures ranged from -2.2 to 41.1°C (average 23.3°C). Partial correlations between temperature and the mean frequency or duration per hour of each behavior category, while controlling for the effect of infant age, indicated that temperature had a significant overall effect on several behaviors related to contact and proximity. Ventroventral contact and huddling the infant were significantly negatively related to temperature, while the frequency of making and breaking contact with the infant were positively related to temperature. In addition, temperature was related to other behaviors at particular weeks of infant age. This study indicates that temperature should be considered as an important variable in understanding nonhuman primate mother-infant behavior.]