In superflat worlds, in biomes where it snows above a height within the build limit, the snowline is about 128 blocks lower than expected. For example, in taiga biomes, where it normally snows above around Y=160, the snow line is somewhere around Y=30. This is causing some ponds and rivers to freeze over in my creative world (which is superflat).

Here is every biome affected by the bug: Taiga, Old Growth Pine/Spruce Taiga, Windswept Hills, Windswept Gravelly Hills, and Frozen Ocean. In theory, this applies to all biomes, but these are the only biomes where it has a noticeable effect.

Steps to reproduce:

1. Create a superflat world.
2. Use /fillbiome to set an area to one of the biomes listed above (or simply set the biome on world creation to be one of these)
3. Change weather to rain
4. Observe that it snows lower than expected