Ashe, Tryndamere, and Sejuani are all from Freljord and all dressed inappropriately for the cold weather. This is because the people of Freljord have developed higher body temperatures to protect them from the cold. Because their body temperatures are so high, they must wear less clothing when they go to warmer places like Summoner's Rift.
Why do Ezreal's abilities increase his attack speed?
Why is Yi the Dunkmaster?