Waiting for one to feather out or hope she manages on her own?

Our small flock is close to being ready to take up residence in their new coop/run ( I suspect two more weeks with how rapidly their feathers are coming in ). But alas, one of the five is well behind the others. I suspect she is probably a few days younger, but in general, has been the weakest link, so to speak. Would it be unkind of me to put her out with the others, when she likely will not be as feathered as they? I don't want to separate them. We live in Alpine, CA where the weather as of late has been unpredictable to say the least. 85 one day and 50 the next (nights never dip below 45).

They are currently in the garage in the brooder with the heat light. However, the brooder is now a kennel, so open wire sides. I plan to take the light away to assist in adjusting before they go out to the coop. Think she will fare well despite her being a bit behind the curve? She is otherwise a healthy, active chick. On nights when it has been significantly colder, she seems equally as tolerant as the other chicks.

How long have you had them? If you have had them for say four weeks and are about to start to wean them off heat for a week or two, the one that is behind should catch up. Being introduced to colder temperatures tends to promote feathering. At five to six weeks even being partially feathered their tolerance to cold should be enough to take fifty degrees. It would be unkind to separate her just for her being slower to feather out. Separating her away from the others could cause problems when you go to put her back with the others as you may have then weakened her position in the pecking order.

Thanks, I appreciate the feedback. They are 3 weeks now. The plan is to start weaning them from the light next week. I will be out of town for a week the following and then hope to get them out in the coop upon my return. I agree with not separating her - would likely cause more harm than good. Hopefully I didn't doom her when I started calling her "Meat"...

Make them a 'huddle box', put it in the brooder after turning off the heat(you might have to 'persuade' them to use it) then move it out to the coop with them.
Cardboard box with a bottom a little bigger than what they need to cuddle next to each other without piling and tall enough for them to stand in.
Cut an opening on one side a couple inches from bottom and big enough for 2-3 of them to go thru at once.
Fill the bottom with some pine shavings an inch or so deep.
This will give them a cozy place to sleep/rest, block any drafts and help hold their body heat in.