Don't worry about the ecosystem thing XD Let me explain:

We usually fly in the troposphere, where the height is inversely proportional to the temperature. And it's dangerous if any of wing joint is frozen due to the hot air from flying movement rapidly freeze in low-temperature condition, which will alter the airflow of dragon's wings, therefore reduce the lifting power. Especially in the sky above the forest, having more evapotranspiration will make this phenomenon more significant that enough to cause a real problem during the flight.



So a mechanism to prevent this from happening is needed.



Since I can cast spells, so based on the knowledge above we cast a spell that drains the heat before the freeze. But remember, the spell still working before landing, so nearby ground objects may be affected by the by-product of this spell: cold energy(though cold isn't count as an energy scientifically, better understanding to folks). Frozen just a temporary phenomenon, it'll end as soon as the spell ends and won't cause too much damage to the ecosystem in summer.