I spent some time dinghy sailing with this on a cloudy, breezy day when the air and water temps were hovering just above 65, which was probably pressing the top’s lower design limits. At first, I was skeptical about how well the stretch fabric would keep my arms warm, especially with a lot of spray. I brought my dinghy top along just in case, but I never needed it. My arms were certainly not as warm as my torso, which was nice and toasty, but that was fine, probably because I was actively trimming and steering. Maybe a full day on the water in those conditions, and I might have wanted a spray top over it, but for a few hours in those lower temps, it was fine.