on it's own it would be fine - under another layer it might get too warm above 20 degrees C but would be fine below 20, although it is claimed that they regulate temperature so that they keep you warm in winter and cool in summer.
It goes under ''conversation'' in your inbox on here. Curiously, I was out in a DHB baselayer with a thin jersey over it (about 18 degrees but I like to be very warm). Owing to a bit of incompetence I managed to go over the handlebars and over a bonnet before landing in a heap on the ground. Though my elbow hit the road first it didn't even mark the baselayer! Well, apart from the roadmuck, that is; the fabric is undamaged. Not the kind of test you'd want to regularly give your clothing but it passed.
