BACKGROUND: Although changes in skin depend on the external environment, researchers have performed only a few studies on effect of the actual environment. Most studies have researched skin characterization based on changes in the humidity or temperature. AIM/OBJECTIVE: This study aimed to evaluate changes in the skin based on the difference in indoor and outdoor temperatures and humidity during summer in South Korea and Southeast Asia. METHODS: Twenty-two female participants aged 25-39 years were included. Skin hydration, sebum (cheek, forehead), colour, transparency and pores of the participants were measured after a 30-min exposure to high temperature and high humidity (HTHH) environment and a 30-min exposure to low temperature and low humidity (LTLH) environment. Subsequently, exposure to HTHH environment for 30 min +LTLH environment for 30 min was performed after a total of 1 h and repeated. RESULTS: Repeated exposure to HTHH and LTLH environments increased the skin's sebum content and haemoglobin index. Additionally, skin elasticity was significantly reduced, with patients in their 30 s showing greater changes than those in their 20 s. CONCLUSION: Repeated differences in temperature and humidity cause skin ageing, loosen skin vessels and reduce skin elasticity, thereby leading to skin ageing.