In cold biomes it rains from Y 315 through Y 369

Steps to reproduce

1. Create a world in a cold biome, for example, using "jagged peaks" or "snowy village" from the seed picker.
2. Change weather to rain.
3. Fly upward to Y 375.

Expected result

It's snow all the way up.

Observed result

Rain occurs from Y 315 to Y 369. It blends with the snow for a few blocks at each end and is rain alone from about Y 321.5 through Y 354.5.