Snow, not snow

[KBaker71]

My daughter was driving home in a snowstorm and found a nearly-frozen hen on the side of the road (A white leghorn. In a snow drift. She couldn't see 5 feet in front of her car! What are the odds?). Long story short, I have Snow in the house. She looks to be between 9-12 weeks, which is old enough to be outside in the coop, but she has a cough. The overnight temps are dipping into the single or negative digits (and probably will for the next month). I had already planned on keeping Snow inside for a good week to make sure her cough isn't bird flu related, but when do I officially leave her outside? And what should the daytime temp be for her to spend some time outside (just a few minutes here and there, to start with)?

Side note: she is talking, eating and drinking normally, but still seems a bit weak. She can jump onto a perch 18" off the ground and likes to roam around the room, but only in short stints.

 

[coach723]

You have other birds? If so, she should be kept quarantined for at least 14 days, I would recommend 30 days. A cough is concerning and I would hate for her to bring in a respiratory virus that infects your other birds. There are several common virus's as well as the bird flu.
I would check her over thoroughly for any injuries or wounds, and for any lice/mites. And deal with those if needed.
https://the-chicken-chick.com/poultry-lice-and-mites-identification/
Beyond that, I would feed her well, monitor droppings for abnormalities and let her recover and get stronger. For now, once strong enough you can take her out for short periods during the warmer part of the day. Then you will need to slowly acclimate her to the outdoors once she's healthy enough. Once she's truly healthy she should be able to handle outdoor temps as long as she has a coop to get out of the wind and rain.