Molly, with respect, you say you've lived in italy for a long time? Maybe you're more acclimatised than you realise? Coming straight from Britain, and recently having day time temps of 1-2c and it feeling more like –5c, plus 11c in italy with out breaks of sun shine feels practically tropical! Lol
The only reason i wasnt walking around in shorts yesterday was that I was getting stared at for just being in a T-shirt when the locals have got scarves on, and back home I'm normally the one who's freezing in a jumper when everyone else has bare arms. It turns chilly, though not cold after dark. If you're from up north you'll probably have your bikini on! Lmao
I agree though, bring layers to wear, I've got a leather jacket, that with just a T-shirt underneath is slightly too warm, but its slightly too cool out of the sun shine with just a T-shirt (for my liking). I'll let you know my verdict of wednesdays weather when it happens.
As for UV factor, I'm not the one to ask as I'm dark skinned (though white) and never wear cream in the uk , don't burn, go straigt to brown, would only wear a low factor in the Med in the middle of summer, more often nothing. The sun at the moment is warm, but not intense.