Here's what they would wear during winter.
Max: His standard hoodie.
Nikki: A green long sweat shirt and blue sweat pants with no scarf or hat OR glove
Neil: He wouldn't go outside
Dolph: He would wear a ranger sweat outfit
Ered: Shes to cool to go outside, she'll just sit outside with ear muffs
Harrison: His magic hat, and a yellow sweat shirt with dark yellow sweat pants
Nerris: A weird E-Bay magic sweat outfit
Nurf: Yellow sweat shirt and green pants with yellow gloves
Gwen: Shed stay inside watching movies
David: He'd pull down his sleeves for once, yet he'd put on dark green sweat pants still wearing his scarf
Daniel: He hates snow, that's all
Space kid: Standard space outfit
Quatermaster: He'd hide in his shed until it's September
Edward: Honestly hed also just not go outside
Snake: Standard outfit
Tabii: Shed try to wear something pretty for Neil
Erin: Shed have a sweat shirt on that says: my bff is here 👈
Sasha: Same with Erin 👉
Mr Campbell: No words he's stay inside
Jen: Same outfit as Gwen, but white and grey
Preston: What he wore in that one episode