In Greek mythology, Hades kidnapped Persephone to be his wife. Zeus ordered Hades to return her to Demeter, the godess of the Earth and her mother. However, Hades tricked Persephone into eating the food of the dead, so Zeus decreted that Persephone would spend six months with Demeter and six months with Hades. During the time her daughter is with Hades, Demeter becomes depressed and causes winter.
– Fom Wikipedia, somehow looking up the greek origin of Winter interested me.