This hoodie really is quite amazing. Several shoulder-season hikes after receiving it, I can confirm that it regulates temperature in varying activity levels almost like magic. It's as warm as a much thicker, heavier fleece would be due to the effectiveness of its wind-blocking outer layer. Its inner also shunts any sweat that does build up inside away from your skin quite effectively. Definitely be sure to size it so it fits close to your body. I'm usually on the cusp of men's M and S, and went for the S- it fits me perfectly. I also found it worked much better when I loosened my sternum strap just a bit more than normal, to provide more airflow to the pit vents and upper back.