transitioning chickens to real weather

Hello Permies! I write you on this day to ask for your advice on bringing chickens out into their coop after they have been spending the nights in our house. It is already late October, but our chickens have yet to experience temperatures much below 50, being outside only during the day. We finally completed their coop today and and have them outside for the night, going down to 51 Fahrenheit, which is well within their experience, but the next few nights are looking quite a bit colder, with lows of 46, 36, 36 again, and then 31(below freezing) after that. This is obviously the natural weather for this time of year, but we worry they haven't acclimated yet, as they have been sheltered from the colder nights we've been having. We've been avoiding heating the house, so it still gets chilly, but might only go down to 60 on a 45 degree night.

Even though they are 5 and a half months old at this point, they also seem to be a little behind on their growth due to spending far too long eating feed contaminated by grain mites. Though they have gained some weight since switching to real food, we are still a little worried this stress has them a few steps behind on being ready for this winter. Could the combination of lack of exposure to cold and earlier malnutrition mean their feathers haven't grown in as fully as they need to? It does seem a little worrisome, these are our babies and we care about them very much!

So I have to wonder, does this seem risky to their health? If so what can we do to help make up for their lack of transition time? Obviously we can't continue keeping them inside. We are considering building a blanket fort above them to catch a little heat without inhibiting good air exchange with the more ventilated parts of the coop, but also wonder if there are any steps we could take that we haven't thought of.

I tend to put my chickens out when they have gotten their feathers. If they have a hen house to get in that will keep them sheltered from rain and wind they should be fine. Chickens will huddle together for warmth, if you are really worried about them you could put a light bulb in the hen house.

if they’re fully feathered, i’d expect them to be fine.

The cold weather can help trigger growth. In chickens this is growing a thick set of feathers. For other animals it is a thick coat of fur.

I have seen farms that put chicks out on pasture earlier than the normal 6 weeks, and they almost always get their feathers earlier than the exact same chickens from the exact same hatchery who were kept in a climate controlled brooder the full 6 weeks.

That is the long way of saying, the chickens should be fine. They do not get as cold as we would under the same circumstances.