If you think there's a particularly drafty spot, screw in a thick cardboard over the spot inside, then remove it in summer.My coop is designed for hot weather. It’s drafty if it’s windy. The girls don’t want to come in the house to get dry. I’m not the rooster guy, Mr Wyandottey is their rooster.
If they feel really cold they will keep moving to find a comfortable spot & snuggle for warmth ~ you have a lot of birds to keep each other warm. My understanding is moist air is more problematic in a coop than cold temps.
When it's windy daytime here all our 6 birds come to the garage/house corner where there's no draft & huddle near each other. Nighttime they huddle in the coop. Summertime they spread out more.
Garage/house corner where the chickens found the best place to be whether it's rainy or windy. The Silkies will go inside the coop if we get the bad Santa Ana Winds like the winds that fueled the L.A. fires earlier this year.