Wore this over a synthetic t-shirt along with a day pack for an 18-mile day hike. Weather stuck between mid 60-70's F with a pretty strong breeze. It was a little warm under the mid day sun, but an added bonus which I read through another review was that the material seems just thick/loose enough to keep mosquito's off (except for around the forearm/elbow where I had the sleeves pulled up and tight). Overall I would say the upper comfort limit for the Livingston is in the 60's F depending on how well you regulate heat. I bought the size M as a 6'1" male, 175lbs, and athletic build. The sleeves sit right at the wrist and the overall length falls below my pants waistline which allows the kangaroo pouch to sit below my hip belt for a little extra secure storage as an added bonus. Great product overall.