I have worn my in the cold weather and it kept my head toasty warm. Based on original photos I''ve seen of the cap being worn in Burma, North Africa, and the Adriatic, I decided to wear it during a re enactment in the Nevada high desert heat. I thought it would be too hot, but I was wrong. After sweating, the wool retained the moisture and kept my head cool. I was surprised. A great cap for a great price.
Ray - California