@divanthesimmer and @Huiiie_07 Hot Weather and Cold Weather outfits are indeed patched into the core game, and do not require Seasons. I believe it was patched in with Seasons' release, and very likely was done so so that they could design premade Sims in other packs to have those outfits for Seasons even if you didn't have Seasons installed. That way, future premades wouldn't have randomly generated outfits and could be fully cohesive Sims.
You don't ever use them if you don't have Seasons, but the tabs exist in CAS.
