I teach in a middle school and we don't let the kids out if it is below freezing. So, I guess I didn't think I would need to give explicit directions to NOT take her out in the cold, because I assumed no person in their right mind would take a group of 4 and 5 year olds outside when it was 22 degrees below freezing. I only found out because she had on a different shirt when I came to pick her up and she said it was because her shirt was wet from playing outside. Her winter coat had not been zipped up far enough and the heavy sweater I put on her in the morning over a T-shirt had been taken off earlier because she was too hot. They didn't put it back on her before she went out, so she just had on a T-shirt under her coat. Her mittens were still wet four hours after they had gone outside. I couldn't even put them on her when I picked her up because they would have been worse than going without.
Fortunately, she has not had too many problems with her lungs in the last year, so I haven't been too worried about her getting sick, but I just don't want to take chances.