Rory - Having mostly grown up in the fairly temperate climates local to Vale, Rory is personally ill-suited for extremes. That said, what he lacks in adaptation he (sort of) makes up for in stubbornness -- given the right motivation he'll trudge through a blinding, wind-whipping blizzard or a sweltering, arid desert, though how far he'd get without proper gear is an open question. Given his strong bent towards logic he'd likely try to dress for the environs and come prepared, though lack of experience would potentially undercut those efforts.
Sean - Vacuo is an unforgiving place. Like any predominantly desert landscape it can be unbearably hot during the day and then dip down past freezing come nightfall; despite not being a native Vacuan Sean still grew up there and is acclimated to the conditions. He would probably need to bundle up like an Eskimo if he found himself wintering over in Atlas or Mantle, but in all but the worst of summer conditions he'd be plenty comfortable in just a t-shirt and jeans.
Budonoki - Much like nature itself, Budonoki prefers mild temperatures but can adapt to nearly any environment given time. That said, the old sage would definitely put a few extra layers on in even a regular winter and seek the cool of a tree's shadow come summer's heat.
Alec - The aging baker and former Huntsman is no stranger to roughing it, nor the heat of a full-blaze oven. His biggest temperature concern is actually old wounds and possibly some early signs of arthritis acting up in the cold, and dressing extra warmly can only do so much for those woes.
Cordell - Despite growing up in Atlas, Cordell has been to a lot of places so far in her piracy career, Vacuo included. While she may not exactly be a fan of the extreme heat she can weather it without a change of wardrobe... which is good, considering how much pride she takes in her pirate outfit.
Micah - One of the upsides of full-body third degree burns is that you tend not to feel much, temperature included -- the obvious downside being the risk of hypothermia and/or heatstroke completely sneaking up on you. If he had a job taking him into extremes of cold or heat he would likely invest in a thermally regulated bodysuit to keep him within safe temps while not inhibiting his freedom of movement.