For most of Hell, occasionally storms brew, but they're weak and never amount to much. But slowly, as the rain only occurs infrequently. A near-permanent cycle of blizzards rage in Niflheim, but peter out rapidly as they leave the Ice Cap. Hela takes credit for them, whether or not she actually causes them. Both some Fallen and some natural bat-like fauna have flight ability.
Some beings try to fly far, far out over the Chaos Ocean.
They observe the same excruciating pain and eventual 'death' as those who try to sail. Those who have tried to overcome this effect and continue onwards, away from the Mainland and into the Unknown of the Chaos Ocean have never returned. There are rumors of a Great Northern Waste and a distant Western Land named Alukah, but they have never been substantiated due to the fact that they are well beyond the 'safe range' of ocean travel. The sky is clear to a high 'ceiling' of clouds, which are red, thick, opaque and roiling. The clouds never part, and the source of the constant light is unknown.