One thing we love to do on cold evenings when we're finishing the chicken chores for the night is to pick up one of our Embden geese and slide our hands up under their wings. Ooooh, such soft warmth, what bliss! They wear their goose-down ski jackets all year 'round and it's on nights like these that they're glad they do.
I figure that since many folks keep poultry in much colder & snowier climates than this that my birds will do fine during our all-too-infrequent cold snaps. As long as they're protected from direct cold winds they shouldn't have any problems.
I like how the chickens look on cold mornings, they puff out their feathers and all look so plumpy & full. My poor guinea wishes that she had a scarf for her bare neck, she hunches up her shoulders and pulls her neck into the feathers, looking like a lady wearing a coat with a fluffy fur collar. I imagine her thinking "It never got this cold back in Africa!"