Just like there are some people naturally accustomed to cold, there are some who take to the heat, too. I just finished a run in 81 degree weather wearing a mid-weight thermal shirt. Below 80 degrees and I start to get chilled, but yet, I can run a daily 3 miles in 105 degree weather.(steve C thought that I was nuts because I was wearing a zip up thermal shirt during our 70-80degree hike up and down Whitney)
