I'm a skinny person and with this as an inside layer, my body is pretty warm.  Since I'm skinny (5'7'' and only 127 lbs) and is not in shape, I get cold easily.  There are several times where I still a bit of chill while wearing 3 layers (a regular tshirt, this underarmor shirt and a hooded sweater.  Not sure about the degree of coldness, but I live in San Diego and the several times that I get the chill, I'm guessing it was about 40 degree or so.  I would buy this again :)