2 year old DS will ONLY wear....
Or, pack some socks/shoes and warmer clothes when you go out.....if he gets cold you're all set my DD is pretty choosy with clothes too. We mostly go with it...I believe it's just a "I can do it and make choices" thing. We pack "appropriate" clothing rather than turn it into a battle. She dresses herself and loves having that independence.
Depending how much you go outside, it is manageable. My teen love flip flops and will wear them in the snow, but just to run into the store. For playing in the snow I would insist on weather appropriate clothing.
Ha, we've had the opposite problem all summer long - 2.5 yo DD will only wear long sleeved PJs! We've had a lot of funny looks and comments too. The poor girl was sweating in the heat, but trying to get her to wear anything else resulted in major meltdowns. And it did bug me too - my kid was definitely the only one at the beach wearing long PJs. We kind of just went with it and tried not to make too much of a fuss, and after a couple of months, she didn't insist quite so strongly. At that point, I started to tell her that she could wear her PJ shirt, but she had to wear "real" pants, shorts, or a skirt. It caused some whining at first, but after a few days, she didn't complain. It's been about 5 months since the PJ habit started and she will now wear real clothes without making a fuss. Do you think that when it gets cold enough outside, he'll be disappointed because there are certain activities he won't be able to do wearing shorts and sandals? That's how I finally got my DD to wear a bathing suit instead of PJs - we can't wear PJs into the swimming pool. Good luck - it's just a phase that will pass. Toddlers sure are funny little creatures;-)