I love what Barbara Coloroso has to say about making sure that everyone's dignity remains intact, and I've been trying to keep this in mind as we go through each day, in all situations...but getting my toddler ready to go outside usually involves a huge physical struggle, anger and tears (from both of us). Not very dignified.
So what do you do? Muscle your kid into their winter gear and force them outside in the interest of not going stir crazy INside, or do you let it slide and only take them out when they're willing?
I don't know if there's any magic solution. I know when my oldest was 2 she went through an anti-winter-clothes phase too and I ended up just lugging her around in an amautiq most of the time. She'd wear shorts and a t-shirt and a winter hat and slippers, and when we'd ride the bus she'd climb out when we got on, and climb back in before we got to our stop. When I needed her to wear snow-gear to play outside she'd usually just wear the snowsuit with nothing underneath. It was a very weird time, but it was just a phase, and she outgrew it eventually.
Definitely look for lightweight knit mittens or gloves; they're not as warm, but at least he'll have some dexterity.
I had to insist on leaving the house most days in every weather, because my kid went to preschool/childcare while I was working. However, if he balked at wearing a particular garment, I'd just bring it along. (Mine wasn't a nudist, though--obviously, there's some minimum clothing!) Often he'd announce, "I ready for hat now," after a brief experience of the outdoors. But sometimes he actually was comfortable being much less bundled-up than I thought was appropriate, and that's still the case. I just wrote about choosing my battles on this issue vs. letting him decide:
Mama to a boy EnviroKid 9 years old and a new little girl EnviroBaby !
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My streaker does like minimal layers outside but will concede to winter clothes now that she knows she can't remain outside without them. Only too a few trips outdoors with light jacket and no mittens, and once I saw her hands getting cold/red that was it playtime ended. She didn't like that too much and has been better. She does have a super duper warm lined sweatshirt from LL Bean that's not bulky an I can usually get away with that and a turtleneck on her and she stays pretty warm. She will wear snow pants with leggings or tights underneath. It also helps that lately she wants to "match" me and wears what I wear.