You've covered pretty much all the bases already, the only thing I'd add is... lens fogging.
With the smaller drones in particular, you can end up with condensation between the actual lens element and the 'glass' fitted into the front part of...
I wouldn't rule out cold days entirely. There are folks on the forum who fly actively in Alaska and similar climates throughout the year. Just watch for periods when the wet-bulb temperature is near the dry-bulb temperature, i.e. very high...
Icing is a huge concern. On a drone it just adds weight but it can add up.
Don't fly through clouds.
Flying near waterfalls is where you could find freezing mist. That can accumulate very fast.
probably not a big detail, but sometimes, obstacle avoidance works fine when leaves are on trees and fails when the leaves are gone from thin branches
not that I've ever encountered that problem because I never screw up....uh huh