Summary Background Sunlight damages human skin, resulting in a wrinkled appearance. Human skin temperature, measured inside the dermis by a needle-type thermometer, can be increased up to about 40 °C in direct summer midday sunlight within 15–20 min, and this heat may contribute significantly to sun-induced skin damage. Recent studies suggest that heat as well as UV may play an important role in premature skin aging. However, our knowledge about the effects of heat or infrared light, which certainly increase the temperature of the skin and may possibly interfere with or enhance the damaging effects of UV, on the development of skin aging is limited. Objectives This review provides an outline of the thermal effects on skin aging process in human skin.