YANBU at ALL! This kind of shite does my head in. People who always have to say something.
With me - it's 'aren't you COLD?!' I very rarely get cold, and have bare arms even in Autumn and winter (unless it's less than 5 degrees C.) I just don't get cold very often. At LEAST once or twice a month, someone (usually another woman,) feels the need to say 'aren't you cold?!' 'You must be freezing!' 'ooooh you need a cardy on!' etc etc etc.... And one woman about 20 years older than me said last year 'you are a very silly girl not wrapping up properly in this cold weather!' I'm in my fucking 50s.
I am NOT a silly little girl! I just said 'I'm fine thanks!' 
I also go for walks - even when it's a bit cooler - or raining, and wear open toed sandals as they keep my feet cool - and if they get wet, they dry quickly. Last October, a woman I had never seen before (about 10 years YOUNGER than me,) felt the need to point at me randomly, and say 'what on earth have you got on your feet? Put some sensible shoes on that suit the weather!' I just looked at her like >>>
and said 'I'm fine thank you. I'm a big girl, I can look after myself, and my shoes are fine.' She shook her head and said 'for goodness sake!' I was gobsmacked. I thought 'who the actual fucking hell do you think you are?'
Same story when me and DH were at a tourist attraction last summer. It was 19 degrees C, but a bit overcast and I was warm and was wearing knee-length shorts and a vest top. A woman (around 20 years older again,) stopped right in front of me, and said 'YOU NEED TO WRAP UP! Why are you dressed in skimpy clothes in this weather?' I was actually quite angry, and just ignored her and walked past her. She said 'er hello, I'm speaking to you!' DH said 'oh she doesn't really feel the cold.' I said 'don't fucking explain anything to this random woman. I don't even know who she is!'
She looked disgusted - like I'd shat in her mouth. Again, I thought who the fuck does she think she is?!
This isn't just 'making conversation!' It's fucking nosey and intrusive, and I WILL tell you to mind your own business, or ignore you, or tell you to FUCK OFF. Depending on what mood you catch me in.