Venous leg ulcers have a multifactorial origin. The environmental temperature appears to distinctly modulate the initiation and the subsequent evolution of the leg ulcer. The chronobiology of both episodes is quite distinct. A cold climate favors the initiation while a warmer climate tends to aggravate the ulcer. The seasonal fluctuations of the ulcer process are likely correlated with vasomotor phenomena taking place in the skin following variation in ambient temperature.