Connor (laryngotracheobroncho malacia) flares up from dry air, so sometimes it's hot AND cold. When we turned our heat on for the winter, he had a bloody nose for the first few days, and his malacias started acting up. We just spent last week in Michigan where they have a ton of snow, but the air was much drier than where we live, and he ended up with bloody lips and a raspy cough. Nothing terrible, but dryness is definitely a trigger for him. We have a fire place in our house, but we have to limit his exposure because his little lungs can't handle it.
My mom would take my sister (asthma and symptomatic CF carrier) to stand in front of the freezer when her breathing would get bad at night, so the cold dry air of the freezer was good for her. My brother, though (recurrent bronchitis) she would take into a steamy bathroom (run the water on as hot as it would go) so he responded to hot moist air. Each kid is different, I guess.